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Yoast\WP\Lib

ORM{} Yoast 1.0

Yoast ORM class.

Based on Idiorm

URL: http://github.com/j4mie/idiorm/

A single-class super-simple database abstraction layer for PHP. Provides (nearly) zero-configuration object-relational mapping and a fluent interface for building basic, commonly-used queries.

BSD Licensed.

Copyright (c) 2010, Jamie Matthews All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

  • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

The methods documented below are magic methods that conform to PSR-1. This documentation exposes these methods to doc generators and IDEs.

Хуки из класса
Возвращает

Null. Ничего.

Использование

$ORM = new ORM();
// use class methods

Методы

  1. __construct( $table_name, $data = [] )
  2. __get( $key )
  3. __isset( $key )
  4. __set( $key, $value )
  5. __unset( $key )
  6. add_condition( $type, $fragment, $values = [] )
  7. add_having( $fragment, $values = [] )
  8. add_having_no_value( $column_name, $operator )
  9. add_having_placeholder( $column_name, $separator, $values )
  10. add_id_column_conditions()
  11. add_join_source( $join_operator, $table, $constraint, $table_alias = null )
  12. add_order_by( $column_name, $ordering )
  13. add_result_column( $expr, $alias = null )
  14. add_simple_condition( $type, $column_name, $separator, $value )
  15. add_simple_having( $column_name, $separator, $value )
  16. add_simple_where( $column_name, $separator, $value )
  17. add_where( $fragment, $values = [] )
  18. add_where_no_value( $column_name, $operator )
  19. add_where_placeholder( $column_name, $separator, $values )
  20. as_array()
  21. avg( $column )
  22. build_conditions( $type )
  23. build_group_by()
  24. build_having()
  25. build_insert()
  26. build_join()
  27. build_limit()
  28. build_offset()
  29. build_order_by()
  30. build_select()
  31. build_select_start()
  32. build_update()
  33. build_where()
  34. call_aggregate_db_function( $sql_function, $column )
  35. count( $column = '*' )
  36. count_null_id_columns()
  37. create( $data = null )
  38. create_instance_from_row( $row )
  39. create_model_instance( $orm )
  40. create_placeholders( $fields )
  41. delete()
  42. delete_many()
  43. distinct()
  44. execute( $query, $parameters = [] )
  45. find_array()
  46. find_many()
  47. find_one( $id = null )
  48. for_table( $table_name )
  49. force_all_dirty()
  50. full_outer_join( $table, $constraint, $table_alias = null )
  51. get( $key )
  52. get_compound_id_column_values( $value )
  53. get_compound_id_column_values_array( $values )
  54. get_id_column_name()
  55. get_sql()
  56. get_update_sql()
  57. group_by( $column_name )
  58. group_by_expr( $expr )
  59. having( $column_name, $value = null )
  60. having_equal( $column_name, $value = null )
  61. having_gt( $column_name, $value = null )
  62. having_gte( $column_name, $value = null )
  63. having_id_is( $id )
  64. having_in( $column_name, $values = null )
  65. having_like( $column_name, $value = null )
  66. having_lt( $column_name, $value = null )
  67. having_lte( $column_name, $value = null )
  68. having_not_equal( $column_name, $value = null )
  69. having_not_in( $column_name, $values = null )
  70. having_not_like( $column_name, $value = null )
  71. having_not_null( $column_name )
  72. having_null( $column_name )
  73. having_raw( $clause, $parameters = [] )
  74. hydrate( $data = [] )
  75. id( $disallow_null = false )
  76. inner_join( $table, $constraint, $table_alias = null )
  77. is_dirty( $key )
  78. is_new()
  79. join( $table, $constraint, $table_alias = null )
  80. join_if_not_empty( $glue, $pieces )
  81. left_outer_join( $table, $constraint, $table_alias = null )
  82. limit( $limit )
  83. max( $column )
  84. min( $column )
  85. normalise_select_many_columns( $columns )
  86. offset( $offset )
  87. offsetExists( $key )
  88. offsetGet( $key )
  89. offsetSet( $key, $value )
  90. offsetUnset( $key )
  91. order_by_asc( $column_name )
  92. order_by_desc( $column_name )
  93. order_by_expr( $clause )
  94. quote_identifier( $identifier )
  95. quote_identifier_part( $part )
  96. quote_one_identifier( $identifier )
  97. raw_execute( $query, $parameters = [] )
  98. raw_join( $table, $constraint, $table_alias, $parameters = [] )
  99. raw_query( $query, $parameters = [] )
  100. reset_idiorm_state()
  101. right_outer_join( $table, $constraint, $table_alias = null )
  102. run()
  103. save()
  104. select( $column, $alias = null )
  105. select_expr( $expr, $alias = null )
  106. select_many()
  107. select_many_expr()
  108. set( $key, $value = null )
  109. set_class_name( $class_name )
  110. set_expr( $key, $value = null )
  111. set_orm_property( $key, $value = null, $expr = false )
  112. sum( $column )
  113. table_alias( $alias )
  114. update_many()
  115. use_id_column( $id_column )
  116. where( $column_name, $value = null )
  117. where_any_is( $values, $operator = '=' )
  118. where_equal( $column_name, $value = null )
  119. where_gt( $column_name, $value = null )
  120. where_gte( $column_name, $value = null )
  121. where_id_in( $ids )
  122. where_id_is( $id )
  123. where_in( $column_name, $values )
  124. where_like( $column_name, $value = null )
  125. where_lt( $column_name, $value = null )
  126. where_lte( $column_name, $value = null )
  127. where_not_equal( $column_name, $value = null )
  128. where_not_in( $column_name, $values )
  129. where_not_like( $column_name, $value = null )
  130. where_not_null( $column_name )
  131. where_null( $column_name )
  132. where_raw( $clause, $parameters = [] )

Заметки

Код ORM{} Yoast 15.2

<?php
class ORM implements \ArrayAccess {
	/*
	 * --- CLASS CONSTANTS ---
	 */

	const CONDITION_FRAGMENT = 0;

	const CONDITION_VALUES = 1;

	/*
	 * --- INSTANCE PROPERTIES ---
	 */

	/**
	 * Holds the class name. Wrapped find_one and find_many classes will return an instance or instances of this class.
	 *
	 * @var string
	 */
	protected $class_name;

	/**
	 * Holds the name of the table the current ORM instance is associated with.
	 *
	 * @var string
	 */
	protected $_table_name;

	/**
	 * Holds the alias for the table to be used in SELECT queries.
	 *
	 * @var string
	 */
	protected $_table_alias = null;

	/**
	 * Values to be bound to the query.
	 *
	 * @var array
	 */
	protected $_values = [];

	/**
	 * Columns to select in the result.
	 *
	 * @var array
	 */
	protected $_result_columns = [ '*' ];

	/**
	 * Are we using the default result column or have these been manually changed?
	 *
	 * @var bool
	 */
	protected $_using_default_result_columns = true;

	/**
	 * Holds the join sources.
	 *
	 * @var array
	 */
	protected $_join_sources = [];

	/**
	 * Should the query include a DISTINCT keyword?
	 *
	 * @var bool
	 */
	protected $_distinct = false;

	/**
	 * Is this a raw query?
	 *
	 * @var bool
	 */
	protected $_is_raw_query = false;

	/**
	 * The raw query.
	 *
	 * @var string
	 */
	protected $_raw_query = '';

	/**
	 * The raw query parameters.
	 *
	 * @var array
	 */
	protected $_raw_parameters = [];

	/**
	 * Array of WHERE clauses.
	 *
	 * @var array
	 */
	protected $_where_conditions = [];

	/**
	 * LIMIT.
	 *
	 * @var int
	 */
	protected $_limit = null;

	/**
	 * OFFSET.
	 *
	 * @var int
	 */
	protected $_offset = null;

	/**
	 * ORDER BY.
	 *
	 * @var array
	 */
	protected $_order_by = [];

	/**
	 * GROUP BY.
	 *
	 * @var array
	 */
	protected $_group_by = [];

	/**
	 * HAVING.
	 *
	 * @var array
	 */
	protected $_having_conditions = [];

	/**
	 * The data for a hydrated instance of the class.
	 *
	 * @var array
	 */
	protected $_data = [];

	/**
	 * Lifetime of the object.
	 *
	 * @var array
	 */
	protected $_dirty_fields = [];

	/**
	 * Fields that are to be inserted in the DB raw.
	 *
	 * @var array
	 */
	protected $_expr_fields = [];

	/**
	 * Is this a new object (has create() been called)?
	 *
	 * @var bool
	 */
	protected $_is_new = false;

	/**
	 * Name of the column to use as the primary key for
	 * this instance only. Overrides the config settings.
	 *
	 * @var string
	 */
	protected $_instance_id_column = null;

	/*
	 * --- STATIC METHODS ---
	 */

	/**
	 * Factory method, return an instance of this class bound to the supplied
	 * table name.
	 *
	 * A repeat of content in parent::for_table, so that created class is ORM.
	 *
	 * @param string $table_name The table to create instance for.
	 *
	 * @return ORM Instance of the ORM.
	 */
	public static function for_table( $table_name ) {
		return new static( $table_name, [] );
	}

	/**
	 * Executes a raw query as a wrapper for wpdb::query.
	 * Useful for queries that can't be accomplished through Idiorm,
	 * particularly those using engine-specific features.
	 *
	 * @param string $query      The raw SQL query.
	 * @param array  $parameters Optional bound parameters.
	 *
	 * @return bool Success.
	 * @example raw_execute('INSERT OR REPLACE INTO `widget` (`id`, `name`) SELECT `id`, `name` FROM `other_table`')
	 *
	 * @example raw_execute('SELECT `name`, AVG(`order`) FROM `customer` GROUP BY `name` HAVING AVG(`order`) > 10')
	 */
	public static function raw_execute( $query, $parameters = [] ) {
		return self::execute( $query, $parameters );
	}

	/**
	 * Internal helper method for executing statements.
	 *
	 * @param string $query      The query.
	 * @param array  $parameters An array of parameters to be bound in to the query.
	 *
	 * @return bool|int Response of wpdb::query
	 */
	protected static function execute( $query, $parameters = [] ) {
		/**
		 * The global WordPress database variable.
		 *
		 * @var wpdb
		 */
		global $wpdb;

		$show_errors = $wpdb->show_errors;

		if ( YoastSEO()->classes->get( Migration_Status::class )->get_error( 'free' ) ) {
			$wpdb->show_errors = false;
		}

		$parameters = \array_filter(
			$parameters,
			function( $parameter ) {
				return $parameter !== null;
			}
		);
		if ( ! empty( $parameters ) ) {
			$query = $wpdb->prepare( $query, $parameters );
		}

		$result = $wpdb->query( $query );

		$wpdb->show_errors = $show_errors;

		return $result;
	}

	/*
	 * --- INSTANCE METHODS ---
	 */

	/**
	 * "Private" constructor; shouldn't be called directly.
	 * Use the ORM::for_table factory method instead.
	 *
	 * @param string $table_name Table name.
	 * @param array  $data       Data to populate table.
	 */
	protected function __construct( $table_name, $data = [] ) {
		$this->_table_name = $table_name;
		$this->_data       = $data;
	}

	/**
	 * Sets the name of the class which the wrapped methods should return instances of.
	 *
	 * @param string $class_name The classname to set.
	 *
	 * @return void
	 */
	public function set_class_name( $class_name ) {
		$this->class_name = $class_name;
	}

	/**
	 * Creates a new, empty instance of the class. Used to add a new row to your database. May optionally be passed an
	 * associative array of data to populate the instance. If so, all fields will be flagged as dirty so all will be
	 * saved to the database when save() is called.
	 *
	 * @param array|null $data Data to populate table.
	 *
	 * @return bool|Model|ORM
	 */
	public function create( $data = null ) {
		$this->_is_new = true;
		if ( ! \is_null( $data ) ) {
			$this->hydrate( $data )->force_all_dirty();
		}

		return $this->create_model_instance( $this );
	}

	/**
	 * Specifies the ID column to use for this instance or array of instances only.
	 * This overrides the id_column and id_column_overrides settings.
	 *
	 * This is mostly useful for libraries built on top of Idiorm, and will not normally be used in manually built
	 * queries. If you don't know why you would want to use this, you should probably just ignore it.
	 *
	 * @param string $id_column The ID column.
	 *
	 * @return ORM
	 */
	public function use_id_column( $id_column ) {
		$this->_instance_id_column = $id_column;

		return $this;
	}

	/**
	 * Creates an ORM instance from the given row (an associative array of data fetched from the database).
	 *
	 * @param array $row A row from the database.
	 *
	 * @return bool|Model
	 */
	protected function create_instance_from_row( $row ) {
		$instance = self::for_table( $this->_table_name );
		$instance->use_id_column( $this->_instance_id_column );
		$instance->hydrate( $row );

		return $this->create_model_instance( $instance );
	}

	/**
	 * Tells the ORM that you are expecting a single result back from your query, and execute it. Will return a single
	 * instance of the ORM class, or false if no rows were returned. As a shortcut, you may supply an ID as a parameter
	 * to this method. This will perform a primary key lookup on the table.
	 *
	 * @param null|int $id An (optional) ID.
	 *
	 * @return bool|Model
	 */
	public function find_one( $id = null ) {
		if ( ! \is_null( $id ) ) {
			$this->where_id_is( $id );
		}
		$this->limit( 1 );
		$rows = $this->run();
		if ( empty( $rows ) ) {
			return false;
		}

		return $this->create_instance_from_row( $rows[0] );
	}

	/**
	 * Tells the ORM that you are expecting multiple results from your query, and execute it. Will return an array of
	 * instances of the ORM class, or an empty array if no rows were returned.
	 *
	 * @return array
	 */
	public function find_many() {
		$rows = $this->run();

		if ( $rows === false ) {
			return [];
		}

		return \array_map( [ $this, 'create_instance_from_row' ], $rows );
	}

	/**
	 * Creates an instance of the model class associated with this wrapper and populate it with the supplied Idiorm
	 * instance.
	 *
	 * @param ORM $orm The ORM used by model.
	 *
	 * @return bool|Model Instance of the model class.
	 */
	protected function create_model_instance( $orm ) {
		if ( $orm === false ) {
			return false;
		}

		/**
		 * An instance of Model is being made.
		 *
		 * @var Model $model
		 */
		$model = new $this->class_name();
		$model->set_orm( $orm );

		return $model;
	}

	/**
	 * Tells the ORM that you are expecting multiple results from your query, and execute it. Will return an array, or
	 * an empty array if no rows were returned.
	 *
	 * @return array The query results.
	 */
	public function find_array() {
		return $this->run();
	}

	/**
	 * Tells the ORM that you wish to execute a COUNT query.
	 *
	 * @param string $column The table column.
	 *
	 * @return float|int An integer representing the number of rows returned.
	 */
	public function count( $column = '*' ) {
		return $this->call_aggregate_db_function( __FUNCTION__, $column );
	}

	/**
	 * Tells the ORM that you wish to execute a MAX query.
	 *
	 * @param string $column The table column.
	 *
	 * @return float|int The max value of the chosen column.
	 */
	public function max( $column ) {
		return $this->call_aggregate_db_function( __FUNCTION__, $column );
	}

	/**
	 * Tells the ORM that you wish to execute a MIN query.
	 *
	 * @param string $column The table column.
	 *
	 * @return float|int The min value of the chosen column.
	 */
	public function min( $column ) {
		return $this->call_aggregate_db_function( __FUNCTION__, $column );
	}

	/**
	 * Tells the ORM that you wish to execute a AVG query.
	 *
	 * @param string $column The table column.
	 *
	 * @return float|int The average value of the chosen column.
	 */
	public function avg( $column ) {
		return $this->call_aggregate_db_function( __FUNCTION__, $column );
	}

	/**
	 * Tells the ORM that you wish to execute a SUM query.
	 *
	 * @param string $column The table column.
	 *
	 * @return float|int The sum of the chosen column.
	 */
	public function sum( $column ) {
		return $this->call_aggregate_db_function( __FUNCTION__, $column );
	}

	/**
	 * Returns the select query as SQL.
	 *
	 * @return string The select query in SQL.
	 */
	public function get_sql() {
		return $this->build_select();
	}

	/**
	 * Returns the update query as SQL.
	 *
	 * @return string The update query in SQL.
	 */
	public function get_update_sql() {
		return $this->build_update();
	}

	/**
	 * Executes an aggregate query on the current connection.
	 *
	 * @param string $sql_function The aggregate function to call eg. MIN, COUNT, etc.
	 * @param string $column       The column to execute the aggregate query against.
	 *
	 * @return int
	 */
	protected function call_aggregate_db_function( $sql_function, $column ) {
		$alias        = \strtolower( $sql_function );
		$sql_function = \strtoupper( $sql_function );
		if ( $column !== '*' ) {
			$column = $this->quote_identifier( $column );
		}
		$result_columns        = $this->_result_columns;
		$this->_result_columns = [];
		$this->select_expr( "{$sql_function}({$column})", $alias );
		$result                = $this->find_one();
		$this->_result_columns = $result_columns;
		$return_value          = 0;
		if ( $result !== false && isset( $result->{$alias} ) ) {
			if ( ! \is_numeric( $result->{$alias} ) ) {
				$return_value = $result->{$alias};
			}
			// phpcs:ignore WordPress.PHP.StrictComparisons.LooseComparison -- Reason: This loose comparison seems intended.
			elseif ( (int) $result->{$alias} == (float) $result->{$alias} ) {
				$return_value = (int) $result->{$alias};
			}
			else {
				$return_value = (float) $result->{$alias};
			}
		}

		return $return_value;
	}

	/**
	 * Hydrates (populate) this instance of the class from an associative array of data. This will usually be called
	 * only from inside the class, but it's public in case you need to call it directly.
	 *
	 * @param array $data Data to populate table.
	 *
	 * @return ORM
	 */
	public function hydrate( $data = [] ) {
		$this->_data = $data;

		return $this;
	}

	/**
	 * Forces the ORM to flag all the fields in the $data array as "dirty" and therefore update them when save() is
	 * called.
	 *
	 * @return ORM
	 */
	public function force_all_dirty() {
		$this->_dirty_fields = $this->_data;

		return $this;
	}

	/**
	 * Performs a raw query. The query can contain placeholders in either named or question mark style. If placeholders
	 * are used, the parameters should be an array of values which will be bound to the placeholders in the query.
	 * If this method is called, all other query building methods will be ignored.
	 *
	 * @param array $query      The query.
	 * @param array $parameters The parameters. Defaults to an empty array.
	 *
	 * @return ORM
	 */
	public function raw_query( $query, $parameters = [] ) {
		$this->_is_raw_query   = true;
		$this->_raw_query      = $query;
		$this->_raw_parameters = $parameters;

		return $this;
	}

	/**
	 * Adds an alias for the main table to be used in SELECT queries.
	 *
	 * @param string $alias The alias.
	 *
	 * @return ORM
	 */
	public function table_alias( $alias ) {
		$this->_table_alias = $alias;

		return $this;
	}

	/**
	 * Adds an unquoted expression to the set of columns returned by the SELECT query. Internal method.
	 *
	 * @param string      $expr  The expression.
	 * @param null|string $alias The alias to return the expression as. Defaults to null.
	 *
	 * @return ORM
	 */
	protected function add_result_column( $expr, $alias = null ) {
		if ( ! \is_null( $alias ) ) {
			$expr .= ' AS ' . $this->quote_identifier( $alias );
		}
		if ( $this->_using_default_result_columns ) {
			$this->_result_columns               = [ $expr ];
			$this->_using_default_result_columns = false;
		}
		else {
			$this->_result_columns[] = $expr;
		}

		return $this;
	}

	/**
	 * Counts the number of columns that belong to the primary key and their value is null.
	 *
	 * @throws \Exception Primary key ID contains null value(s).
	 * @throws \Exception Primary key ID missing from row or is null.
	 *
	 * @return int The amount of null columns.
	 */
	public function count_null_id_columns() {
		if ( \is_array( $this->get_id_column_name() ) ) {
			return \count( \array_filter( $this->id(), 'is_null' ) );
		}
		else {
			return \is_null( $this->id() ) ? 1 : 0;
		}
	}

	/**
	 * Adds a column to the list of columns returned by the SELECT query.
	 *
	 * @param string      $column The column. Defaults to '*'.
	 * @param null|string $alias  The alias to return the column as. Defaults to null.
	 *
	 * @return ORM
	 */
	public function select( $column, $alias = null ) {
		$column = $this->quote_identifier( $column );

		return $this->add_result_column( $column, $alias );
	}

	/**
	 * Adds an unquoted expression to the list of columns returned by the SELECT query.
	 *
	 * @param string      $expr  The expression.
	 * @param null|string $alias The alias to return the column as. Defaults to null.
	 *
	 * @return ORM
	 */
	public function select_expr( $expr, $alias = null ) {
		return $this->add_result_column( $expr, $alias );
	}

	/**
	 * Adds columns to the list of columns returned by the SELECT query.
	 *
	 * This defaults to '*'.
	 * Many columns can be supplied as either an array or as a list of parameters to the method.
	 * Note that the alias must not be numeric - if you want a numeric alias then prepend it with some alpha chars. eg.
	 * a1.
	 *
	 * @return ORM
	 * @example select_many(array('column', 'column2', 'column3'), 'column4', 'column5');
	 * @example select_many(array('alias' => 'column', 'column2', 'alias2' => 'column3'), 'column4', 'column5');
	 *
	 * @example select_many('column', 'column2', 'column3');
	 */
	public function select_many() {
		$columns = \func_get_args();
		if ( ! empty( $columns ) ) {
			$columns = $this->normalise_select_many_columns( $columns );
			foreach ( $columns as $alias => $column ) {
				if ( \is_numeric( $alias ) ) {
					$alias = null;
				}
				$this->select( $column, $alias );
			}
		}

		return $this;
	}

	/**
	 * Adds an unquoted expression to the list of columns returned by the SELECT query.
	 *
	 * Many columns can be supplied as either an array or as a list of parameters to the method.
	 * Note that the alias must not be numeric - if you want a numeric alias then prepend it with some alpha chars. eg.
	 * a1
	 *
	 * @return ORM
	 * @example select_many_expr(array('alias' => 'column', 'column2', 'alias2' => 'column3'), 'column4', 'column5')
	 * @example select_many_expr('column', 'column2', 'column3')
	 *
	 * @example select_many_expr(array('column', 'column2', 'column3'), 'column4', 'column5')
	 */
	public function select_many_expr() {
		$columns = \func_get_args();
		if ( ! empty( $columns ) ) {
			$columns = $this->normalise_select_many_columns( $columns );
			foreach ( $columns as $alias => $column ) {
				if ( \is_numeric( $alias ) ) {
					$alias = null;
				}
				$this->select_expr( $column, $alias );
			}
		}

		return $this;
	}

	/**
	 * Takes a column specification for the select many methods and convert it into a normalised array of columns and
	 * aliases.
	 *
	 * It is designed to turn the following styles into a normalised array:
	 * array(array('alias' => 'column', 'column2', 'alias2' => 'column3'), 'column4', 'column5'))
	 *
	 * @param array $columns The columns.
	 *
	 * @return array
	 */
	protected function normalise_select_many_columns( $columns ) {
		$return = [];
		foreach ( $columns as $column ) {
			if ( \is_array( $column ) ) {
				foreach ( $column as $key => $value ) {
					if ( ! \is_numeric( $key ) ) {
						$return[ $key ] = $value;
					}
					else {
						$return[] = $value;
					}
				}
			}
			else {
				$return[] = $column;
			}
		}

		return $return;
	}

	/**
	 * Adds a DISTINCT keyword before the list of columns in the SELECT query.
	 *
	 * @return ORM
	 */
	public function distinct() {
		$this->_distinct = true;

		return $this;
	}

	/**
	 * Add a JOIN source to the query. Internal method.
	 *
	 * The join_operator should be one of INNER, LEFT OUTER, CROSS etc - this
	 * will be prepended to JOIN.
	 *
	 * The table should be the name of the table to join to.
	 *
	 * The constraint may be either a string or an array with three elements. If it
	 * is a string, it will be compiled into the query as-is, with no escaping. The
	 * recommended way to supply the constraint is as an array with three elements:
	 *
	 * first_column, operator, second_column
	 *
	 * Example: array('user.id', '=', 'profile.user_id')
	 *
	 * will compile to
	 *
	 * ON `user`.`id` = `profile`.`user_id`
	 *
	 * The final (optional) argument specifies an alias for the joined table.
	 *
	 * @param string      $join_operator The join_operator should be one of INNER, LEFT OUTER, CROSS etc - this will be
	 *                                   prepended to JOIN.
	 * @param string      $table         The table should be the name of the table to join to.
	 * @param string      $constraint    The constraint.
	 * @param string|null $table_alias   The alias for the joined table. Defaults to null.
	 *
	 * @return ORM
	 */
	protected function add_join_source( $join_operator, $table, $constraint, $table_alias = null ) {
		$join_operator = \trim( "{$join_operator} JOIN" );
		$table         = $this->quote_identifier( $table );
		// Add table alias if present.
		if ( ! \is_null( $table_alias ) ) {
			$table_alias = $this->quote_identifier( $table_alias );
			$table      .= " {$table_alias}";
		}
		// Build the constraint.
		if ( \is_array( $constraint ) ) {
			list( $first_column, $operator, $second_column ) = $constraint;

			$first_column  = $this->quote_identifier( $first_column );
			$second_column = $this->quote_identifier( $second_column );
			$constraint    = "{$first_column} {$operator} {$second_column}";
		}
		$this->_join_sources[] = "{$join_operator} {$table} ON {$constraint}";

		return $this;
	}

	/**
	 * Adds a RAW JOIN source to the query.
	 *
	 * @param string $table       The table name.
	 * @param string $constraint  The constraint.
	 * @param string $table_alias The table alias.
	 * @param array  $parameters  The parameters. Defaults to an empty array.
	 *
	 * @return ORM
	 */
	public function raw_join( $table, $constraint, $table_alias, $parameters = [] ) {
		// Add table alias if present.
		if ( ! \is_null( $table_alias ) ) {
			$table_alias = $this->quote_identifier( $table_alias );
			$table      .= " {$table_alias}";
		}
		$this->_values = \array_merge( $this->_values, $parameters );
		// Build the constraint.
		if ( \is_array( $constraint ) ) {
			list( $first_column, $operator, $second_column ) = $constraint;

			$first_column  = $this->quote_identifier( $first_column );
			$second_column = $this->quote_identifier( $second_column );
			$constraint    = "{$first_column} {$operator} {$second_column}";
		}
		$this->_join_sources[] = "{$table} ON {$constraint}";

		return $this;
	}

	/**
	 * Adds a simple JOIN source to the query.
	 *
	 * @param string      $table       The table name.
	 * @param string      $constraint  The constraint.
	 * @param string|null $table_alias The table alias. Defaults to null.
	 *
	 * @return ORM
	 */
	public function join( $table, $constraint, $table_alias = null ) {
		return $this->add_join_source( '', $table, $constraint, $table_alias );
	}

	/**
	 * Adds an INNER JOIN source to the query.
	 *
	 * @param string      $table       The table name.
	 * @param string      $constraint  The constraint.
	 * @param string|null $table_alias The table alias. Defaults to null.
	 *
	 * @return ORM
	 */
	public function inner_join( $table, $constraint, $table_alias = null ) {
		return $this->add_join_source( 'INNER', $table, $constraint, $table_alias );
	}

	/**
	 * Adds a LEFT OUTER JOIN source to the query.
	 *
	 * @param string      $table       The table name.
	 * @param string      $constraint  The constraint.
	 * @param string|null $table_alias The table alias. Defaults to null.
	 *
	 * @return ORM
	 */
	public function left_outer_join( $table, $constraint, $table_alias = null ) {
		return $this->add_join_source( 'LEFT OUTER', $table, $constraint, $table_alias );
	}

	/**
	 * Adds a RIGHT OUTER JOIN source to the query.
	 *
	 * @param string      $table       The table name.
	 * @param string      $constraint  The constraint.
	 * @param string|null $table_alias The table alias. Defaults to null.
	 *
	 * @return ORM
	 */
	public function right_outer_join( $table, $constraint, $table_alias = null ) {
		return $this->add_join_source( 'RIGHT OUTER', $table, $constraint, $table_alias );
	}

	/**
	 * Adds a FULL OUTER JOIN source to the query.
	 *
	 * @param string      $table       The table name.
	 * @param string      $constraint  The constraint.
	 * @param string|null $table_alias The table alias. Defaults to null.
	 *
	 * @return ORM
	 */
	public function full_outer_join( $table, $constraint, $table_alias = null ) {
		return $this->add_join_source( 'FULL OUTER', $table, $constraint, $table_alias );
	}

	/**
	 * Adds a HAVING condition to the query. Internal method.
	 *
	 * @param string $fragment The fragment.
	 * @param array  $values   The values. Defaults to an empty array.
	 *
	 * @return ORM
	 */
	protected function add_having( $fragment, $values = [] ) {
		return $this->add_condition( 'having', $fragment, $values );
	}

	/**
	 * Adds a HAVING condition to the query. Internal method.
	 *
	 * @param string $column_name The table column.
	 * @param string $separator   The separator.
	 * @param mixed  $value       The value.
	 *
	 * @return ORM
	 */
	protected function add_simple_having( $column_name, $separator, $value ) {
		return $this->add_simple_condition( 'having', $column_name, $separator, $value );
	}

	/**
	 * Adds a HAVING clause with multiple values (like IN and NOT IN). Internal method.
	 *
	 * @param string|array $column_name The table column.
	 * @param string       $separator   The separator.
	 * @param array        $values      The values.
	 *
	 * @return ORM
	 */
	public function add_having_placeholder( $column_name, $separator, $values ) {
		if ( ! \is_array( $column_name ) ) {
			$data = [ $column_name => $values ];
		}
		else {
			$data = $column_name;
		}
		$result = $this;
		foreach ( $data as $key => $val ) {
			$column       = $result->quote_identifier( $key );
			$placeholders = $result->create_placeholders( $val );
			$result       = $result->add_having( "{$column} {$separator} ({$placeholders})", $val );
		}

		return $result;
	}

	/**
	 * Adds a HAVING clause with no parameters(like IS NULL and IS NOT NULL). Internal method.
	 *
	 * @param string $column_name The column name.
	 * @param string $operator    The operator.
	 *
	 * @return ORM
	 */
	public function add_having_no_value( $column_name, $operator ) {
		$conditions = \is_array( $column_name ) ? $column_name : [ $column_name ];
		$result     = $this;
		foreach ( $conditions as $column ) {
			$column = $this->quote_identifier( $column );
			$result = $result->add_having( "{$column} {$operator}" );
		}

		return $result;
	}

	/**
	 * Adds a WHERE condition to the query. Internal method.
	 *
	 * @param string $fragment The fragment.
	 * @param array  $values   The values. Defaults to an empty array.
	 *
	 * @return ORM
	 */
	protected function add_where( $fragment, $values = [] ) {
		return $this->add_condition( 'where', $fragment, $values );
	}

	/**
	 * Adds a WHERE condition to the query. Internal method.
	 *
	 * @param string|array $column_name The table column.
	 * @param string       $separator   The separator.
	 * @param mixed        $value       The value.
	 *
	 * @return ORM
	 */
	protected function add_simple_where( $column_name, $separator, $value ) {
		return $this->add_simple_condition( 'where', $column_name, $separator, $value );
	}

	/**
	 * Adds a WHERE clause with multiple values (like IN and NOT IN).
	 *
	 * @param string|array $column_name The table column.
	 * @param string       $separator   The separator.
	 * @param array        $values      The values.
	 *
	 * @return ORM
	 */
	public function add_where_placeholder( $column_name, $separator, $values ) {
		if ( ! \is_array( $column_name ) ) {
			$data = [ $column_name => $values ];
		}
		else {
			$data = $column_name;
		}
		$result = $this;
		foreach ( $data as $key => $val ) {
			$column       = $result->quote_identifier( $key );
			$placeholders = $result->create_placeholders( $val );
			$result       = $result->add_where( "{$column} {$separator} ({$placeholders})", $val );
		}

		return $result;
	}

	/**
	 * Adds a WHERE clause with no parameters(like IS NULL and IS NOT NULL).
	 *
	 * @param string $column_name The column name.
	 * @param string $operator    The operator.
	 *
	 * @return ORM
	 */
	public function add_where_no_value( $column_name, $operator ) {
		$conditions = \is_array( $column_name ) ? $column_name : [ $column_name ];
		$result     = $this;
		foreach ( $conditions as $column ) {
			$column = $this->quote_identifier( $column );
			$result = $result->add_where( "{$column} {$operator}" );
		}

		return $result;
	}

	/**
	 * Adds a HAVING or WHERE condition to the query. Internal method.
	 *
	 * @param string $type     The type.
	 * @param string $fragment The fragment.
	 * @param array  $values   The values. Defaults to empty array.
	 *
	 * @return ORM
	 */
	protected function add_condition( $type, $fragment, $values = [] ) {
		$conditions_class_property_name = "_{$type}_conditions";
		if ( ! \is_array( $values ) ) {
			$values = [ $values ];
		}
		\array_push(
			$this->{$conditions_class_property_name},
			[
				self::CONDITION_FRAGMENT => $fragment,
				self::CONDITION_VALUES   => $values,
			]
		);

		return $this;
	}

	/**
	 * Compiles a simple COLUMN SEPARATOR VALUE style HAVING or WHERE condition into a string and value ready to be
	 * passed to the add_condition method.
	 *
	 * Avoids duplication of the call to quote_identifier.
	 * If column_name is an associative array, it will add a condition for each column.
	 *
	 * @param string       $type        The type.
	 * @param string|array $column_name The table column.
	 * @param string       $separator   The separator.
	 * @param mixed        $value       The value.
	 *
	 * @return ORM
	 */
	protected function add_simple_condition( $type, $column_name, $separator, $value ) {
		$multiple = \is_array( $column_name ) ? $column_name : [ $column_name => $value ];
		$result   = $this;
		foreach ( $multiple as $key => $val ) {
			// Add the table name in case of ambiguous columns.
			if ( \count( $result->_join_sources ) > 0 && \strpos( $key, '.' ) === false ) {
				$table = $result->_table_name;
				if ( ! \is_null( $result->_table_alias ) ) {
					$table = $result->_table_alias;
				}
				$key = "{$table}.{$key}";
			}
			$key         = $result->quote_identifier( $key );
			$placeholder = ( $val === null ) ? 'NULL' : '%s';
			$result      = $result->add_condition( $type, "{$key} {$separator} {$placeholder}", $val );
		}

		return $result;
	}

	/**
	 * Returns a string containing the given number of question marks, separated by commas. Eg "?, ?, ?".
	 *
	 * @param array $fields Fields to create placeholder for.
	 *
	 * @return string
	 */
	protected function create_placeholders( $fields ) {
		if ( ! empty( $fields ) ) {
			$db_fields = [];
			foreach ( $fields as $key => $value ) {
				// Process expression fields directly into the query.
				if ( \array_key_exists( $key, $this->_expr_fields ) ) {
					$db_fields[] = $value;
				}
				else {
					$db_fields[] = ( $value === null ) ? 'NULL' : '%s';
				}
			}

			return \implode( ', ', $db_fields );
		}

		return '';
	}

	/**
	 * Filters a column/value array returning only those columns that belong to a compound primary key.
	 *
	 * If the key contains a column that does not exist in the given array, a null value will be returned for it.
	 *
	 * @param mixed $value The value.
	 *
	 * @return array
	 */
	protected function get_compound_id_column_values( $value ) {
		$filtered = [];
		foreach ( $this->get_id_column_name() as $key ) {
			$filtered[ $key ] = isset( $value[ $key ] ) ? $value[ $key ] : null;
		}

		return $filtered;
	}

	/**
	 * Filters an array containing compound column/value arrays.
	 *
	 * @param array $values The values.
	 *
	 * @return array
	 */
	protected function get_compound_id_column_values_array( $values ) {
		$filtered = [];
		foreach ( $values as $value ) {
			$filtered[] = $this->get_compound_id_column_values( $value );
		}

		return $filtered;
	}

	/**
	 * Add a WHERE column = value clause to your query. Each time this is called in the chain, an additional WHERE will
	 * be added, and these will be ANDed together when the final query is built.
	 *
	 * If you use an array in $column_name, a new clause will be added for each element. In this case, $value is
	 * ignored.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value. Defaults to null.
	 *
	 * @return ORM
	 */
	public function where( $column_name, $value = null ) {
		return $this->where_equal( $column_name, $value );
	}

	/**
	 * More explicitly named version of for the where() method. Can be used if preferred.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value. Defaults to null.
	 *
	 * @return ORM
	 */
	public function where_equal( $column_name, $value = null ) {
		return $this->add_simple_where( $column_name, '=', $value );
	}

	/**
	 * Add a WHERE column != value clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value. Defaults to null.
	 *
	 * @return ORM
	 */
	public function where_not_equal( $column_name, $value = null ) {
		return $this->add_simple_where( $column_name, '!=', $value );
	}

	/**
	 * Queries the table by its primary key. Special method.
	 *
	 * If primary key is compound, only the columns that belong to they key will be used for the query.
	 *
	 * @param string $id The ID.
	 *
	 * @return ORM
	 */
	public function where_id_is( $id ) {
		return \is_array( $this->get_id_column_name() ) ? $this->where( $this->get_compound_id_column_values( $id ), null ) : $this->where( $this->get_id_column_name(), $id );
	}

	/**
	 * Allows adding a WHERE clause that matches any of the conditions specified in the array. Each element in the
	 * associative array will be a different condition, where the key will be the column name.
	 *
	 * By default, an equal operator will be used against all columns, but it can be overriden for any or every column
	 * using the second parameter.
	 *
	 * Each condition will be ORed together when added to the final query.
	 *
	 * @param array  $values   The values.
	 * @param string $operator The operator.
	 *
	 * @return ORM
	 */
	public function where_any_is( $values, $operator = '=' ) {
		$data  = [];
		$query = [ '((' ];
		$first = true;
		foreach ( $values as $value ) {
			if ( $first ) {
				$first = false;
			}
			else {
				$query[] = ') OR (';
			}
			$firstsub = true;
			foreach ( $value as $key => $item ) {
				$op = \is_string( $operator ) ? $operator : ( isset( $operator[ $key ] ) ? $operator[ $key ] : '=' );
				if ( $firstsub ) {
					$firstsub = false;
				}
				else {
					$query[] = 'AND';
				}
				$query[] = $this->quote_identifier( $key );
				$data[]  = $item;
				$query[] = $op . ( ( $item === null ) ? 'NULL' : '%s' );
			}
		}
		$query[] = '))';

		return $this->where_raw( \join( ' ', $query ), $data );
	}

	/**
	 * Queries the table by its primary key.
	 *
	 * Similar to where_id_is() but allowing multiple primary keys.
	 * If primary key is compound, only the columns that belong to they key will be used for the query.
	 *
	 * @param string[] $ids The IDs.
	 *
	 * @return ORM
	 */
	public function where_id_in( $ids ) {
		return \is_array( $this->get_id_column_name() ) ? $this->where_any_is( $this->get_compound_id_column_values_array( $ids ) ) : $this->where_in( $this->get_id_column_name(), $ids );
	}

	/**
	 * Adds a WHERE ... LIKE clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value. Defaults to null.
	 *
	 * @return ORM
	 */
	public function where_like( $column_name, $value = null ) {
		return $this->add_simple_where( $column_name, 'LIKE', $value );
	}

	/**
	 * Adds where WHERE ... NOT LIKE clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value. Defaults to null.
	 *
	 * @return ORM
	 */
	public function where_not_like( $column_name, $value = null ) {
		return $this->add_simple_where( $column_name, 'NOT LIKE', $value );
	}

	/**
	 * Adds a WHERE ... > clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value. Defaults to null.
	 *
	 * @return ORM
	 */
	public function where_gt( $column_name, $value = null ) {
		return $this->add_simple_where( $column_name, '>', $value );
	}

	/**
	 * Adds a WHERE ... < clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value. Defaults to null.
	 *
	 * @return ORM
	 */
	public function where_lt( $column_name, $value = null ) {
		return $this->add_simple_where( $column_name, '<', $value );
	}

	/**
	 * Adds a WHERE ... >= clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value. Defaults to null.
	 *
	 * @return ORM
	 */
	public function where_gte( $column_name, $value = null ) {
		return $this->add_simple_where( $column_name, '>=', $value );
	}

	/**
	 * Adds a WHERE ... <= clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value. Defaults to null.
	 *
	 * @return ORM
	 */
	public function where_lte( $column_name, $value = null ) {
		return $this->add_simple_where( $column_name, '<=', $value );
	}

	/**
	 * Adds a WHERE ... IN clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param array        $values      The values.
	 *
	 * @return ORM
	 */
	public function where_in( $column_name, $values ) {
		return $this->add_where_placeholder( $column_name, 'IN', $values );
	}

	/**
	 * Adds a WHERE ... NOT IN clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param array        $values      The values.
	 *
	 * @return ORM
	 */
	public function where_not_in( $column_name, $values ) {
		return $this->add_where_placeholder( $column_name, 'NOT IN', $values );
	}

	/**
	 * Adds a WHERE column IS NULL clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 *
	 * @return ORM
	 */
	public function where_null( $column_name ) {
		return $this->add_where_no_value( $column_name, 'IS NULL' );
	}

	/**
	 * Adds a WHERE column IS NOT NULL clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 *
	 * @return ORM
	 */
	public function where_not_null( $column_name ) {
		return $this->add_where_no_value( $column_name, 'IS NOT NULL' );
	}

	/**
	 * Adds a raw WHERE clause to the query. The clause should contain question mark placeholders, which will be bound
	 * to the parameters supplied in the second argument.
	 *
	 * @param string $clause     The clause that should contain question mark placeholders.
	 * @param array  $parameters The parameters to include in the query.
	 *
	 * @return ORM
	 */
	public function where_raw( $clause, $parameters = [] ) {
		return $this->add_where( $clause, $parameters );
	}

	/**
	 * Adds a LIMIT to the query.
	 *
	 * @param int $limit The limit.
	 *
	 * @return ORM
	 */
	public function limit( $limit ) {
		$this->_limit = $limit;

		return $this;
	}

	/**
	 * Adds an OFFSET to the query.
	 *
	 * @param int $offset The offset.
	 *
	 * @return ORM
	 */
	public function offset( $offset ) {
		$this->_offset = $offset;

		return $this;
	}

	/**
	 * Adds an ORDER BY clause to the query.
	 *
	 * @param string $column_name The column name.
	 * @param string $ordering    The ordering. DESC or ASC.
	 *
	 * @return ORM
	 */
	protected function add_order_by( $column_name, $ordering ) {
		$column_name       = $this->quote_identifier( $column_name );
		$this->_order_by[] = "{$column_name} {$ordering}";

		return $this;
	}

	/**
	 * Adds an ORDER BY column DESC clause.
	 *
	 * @param string|array $column_name The table column.
	 *
	 * @return ORM
	 */
	public function order_by_desc( $column_name ) {
		return $this->add_order_by( $column_name, 'DESC' );
	}

	/**
	 * Adds an ORDER BY column ASC clause.
	 *
	 * @param string|array $column_name The table column.
	 *
	 * @return ORM
	 */
	public function order_by_asc( $column_name ) {
		return $this->add_order_by( $column_name, 'ASC' );
	}

	/**
	 * Adds an unquoted expression as an ORDER BY clause.
	 *
	 * @param string $clause The clause.
	 *
	 * @return ORM
	 */
	public function order_by_expr( $clause ) {
		$this->_order_by[] = $clause;

		return $this;
	}

	/**
	 * Adds a column to the list of columns to GROUP BY.
	 *
	 * @param string|array $column_name The table column.
	 *
	 * @return ORM
	 */
	public function group_by( $column_name ) {
		$column_name       = $this->quote_identifier( $column_name );
		$this->_group_by[] = $column_name;

		return $this;
	}

	/**
	 * Adds an unquoted expression to the list of columns to GROUP BY.
	 *
	 * @param string $expr The expression.
	 *
	 * @return ORM
	 */
	public function group_by_expr( $expr ) {
		$this->_group_by[] = $expr;

		return $this;
	}

	/**
	 * Adds a HAVING column = value clause to your query.
	 *
	 * Each time this is called in the chain, an additional HAVING will be added, and these will be ANDed together when
	 * the final query is built.
	 *
	 * If you use an array in $column_name, a new clause will be added for each element. In this case, $value is
	 * ignored.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value.
	 *
	 * @return ORM
	 */
	public function having( $column_name, $value = null ) {
		return $this->having_equal( $column_name, $value );
	}

	/**
	 * Adds a having equal to your query.
	 *
	 * More explicitly named version of for the having() method. Can be used if preferred.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value.
	 *
	 * @return ORM
	 */
	public function having_equal( $column_name, $value = null ) {
		return $this->add_simple_having( $column_name, '=', $value );
	}

	/**
	 * Adds a HAVING column != value clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param mixed|null   $value       The value.
	 *
	 * @return ORM
	 */
	public function having_not_equal( $column_name, $value = null ) {
		return $this->add_simple_having( $column_name, '!=', $value );
	}

	/**
	 * Queries the table by its primary key. Special method.
	 *
	 * If primary key is compound, only the columns that belong to they key will be used for the query.
	 *
	 * @param string $id The ID.
	 *
	 * @return ORM
	 */
	public function having_id_is( $id ) {
		return \is_array( $this->get_id_column_name() ) ? $this->having( $this->get_compound_id_column_values( $id ), null ) : $this->having( $this->get_id_column_name(), $id );
	}

	/**
	 * Adds a HAVING ... LIKE clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param null         $value       The value.
	 *
	 * @return ORM
	 */
	public function having_like( $column_name, $value = null ) {
		return $this->add_simple_having( $column_name, 'LIKE', $value );
	}

	/**
	 * Adds where HAVING ... NOT LIKE clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param null         $value       The value.
	 *
	 * @return ORM
	 */
	public function having_not_like( $column_name, $value = null ) {
		return $this->add_simple_having( $column_name, 'NOT LIKE', $value );
	}

	/**
	 * Adds a HAVING ... > clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param null         $value       The value.
	 *
	 * @return ORM
	 */
	public function having_gt( $column_name, $value = null ) {
		return $this->add_simple_having( $column_name, '>', $value );
	}

	/**
	 * Adds a HAVING ... < clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param null         $value       The value.
	 *
	 * @return ORM
	 */
	public function having_lt( $column_name, $value = null ) {
		return $this->add_simple_having( $column_name, '<', $value );
	}

	/**
	 * Adds a HAVING ... >= clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param null         $value       The value. Defaults to null.
	 *
	 * @return ORM
	 */
	public function having_gte( $column_name, $value = null ) {
		return $this->add_simple_having( $column_name, '>=', $value );
	}

	/**
	 * Adds a HAVING ... <= clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param null         $value       The value.
	 *
	 * @return ORM
	 */
	public function having_lte( $column_name, $value = null ) {
		return $this->add_simple_having( $column_name, '<=', $value );
	}

	/**
	 * Adds a HAVING ... IN clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param null         $values      The values. Defaults to null.
	 *
	 * @return ORM
	 */
	public function having_in( $column_name, $values = null ) {
		return $this->add_having_placeholder( $column_name, 'IN', $values );
	}

	/**
	 * Adds a HAVING ... NOT IN clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 * @param null         $values      The values. Defaults to null.
	 *
	 * @return ORM
	 */
	public function having_not_in( $column_name, $values = null ) {
		return $this->add_having_placeholder( $column_name, 'NOT IN', $values );
	}

	/**
	 * Adds a HAVING column IS NULL clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 *
	 * @return ORM
	 */
	public function having_null( $column_name ) {
		return $this->add_having_no_value( $column_name, 'IS NULL' );
	}

	/**
	 * Adds a HAVING column IS NOT NULL clause to your query.
	 *
	 * @param string|array $column_name The table column.
	 *
	 * @return ORM
	 */
	public function having_not_null( $column_name ) {
		return $this->add_having_no_value( $column_name, 'IS NOT NULL' );
	}

	/**
	 * Adds a raw HAVING clause to the query. The clause should contain question mark placeholders, which will be bound
	 * to the parameters supplied in the second argument.
	 *
	 * @param string $clause     The clause that should contain question mark placeholders.
	 * @param array  $parameters The parameters to include in the query.
	 *
	 * @return ORM
	 */
	public function having_raw( $clause, $parameters = [] ) {
		return $this->add_having( $clause, $parameters );
	}

	/**
	 * Builds a SELECT statement based on the clauses that have been passed to this instance by chaining method calls.
	 *
	 * @return string
	 */
	protected function build_select() {
		// If the query is raw, just set the $this->_values to be the raw query parameters and return the raw query.
		if ( $this->_is_raw_query ) {
			$this->_values = $this->_raw_parameters;

			return $this->_raw_query;
		}

		// Build and return the full SELECT statement by concatenating the results of calling each separate builder method.
		return $this->join_if_not_empty(
			' ',
			[
				$this->build_select_start(),
				$this->build_join(),
				$this->build_where(),
				$this->build_group_by(),
				$this->build_having(),
				$this->build_order_by(),
				$this->build_limit(),
				$this->build_offset(),
			]
		);
	}

	/**
	 * Builds the start of the SELECT statement.
	 *
	 * @return string
	 */
	protected function build_select_start() {
		$fragment       = 'SELECT ';
		$result_columns = \join( ', ', $this->_result_columns );
		if ( $this->_distinct ) {
			$result_columns = 'DISTINCT ' . $result_columns;
		}
		$fragment .= "{$result_columns} FROM " . $this->quote_identifier( $this->_table_name );
		if ( ! \is_null( $this->_table_alias ) ) {
			$fragment .= ' ' . $this->quote_identifier( $this->_table_alias );
		}

		return $fragment;
	}

	/**
	 * Builds the JOIN sources.
	 *
	 * @return string
	 */
	protected function build_join() {
		if ( \count( $this->_join_sources ) === 0 ) {
			return '';
		}

		return \join( ' ', $this->_join_sources );
	}

	/**
	 * Builds the WHERE clause(s).
	 *
	 * @return string
	 */
	protected function build_where() {
		return $this->build_conditions( 'where' );
	}

	/**
	 * Build the HAVING clause(s)
	 *
	 * @return string
	 */
	protected function build_having() {
		return $this->build_conditions( 'having' );
	}

	/**
	 * Builds GROUP BY.
	 *
	 * @return string
	 */
	protected function build_group_by() {
		if ( \count( $this->_group_by ) === 0 ) {
			return '';
		}

		return 'GROUP BY ' . \join( ', ', $this->_group_by );
	}

	/**
	 * Builds a WHERE or HAVING clause.
	 *
	 * @param string $type Where or having.
	 *
	 * @return string
	 */
	protected function build_conditions( $type ) {
		$conditions_class_property_name = "_{$type}_conditions";
		// If there are no clauses, return empty string.
		if ( \count( $this->{$conditions_class_property_name} ) === 0 ) {
			return '';
		}
		$conditions = [];
		foreach ( $this->{$conditions_class_property_name} as $condition ) {
			$conditions[]  = $condition[ self::CONDITION_FRAGMENT ];
			$this->_values = \array_merge( $this->_values, $condition[ self::CONDITION_VALUES ] );
		}

		return \strtoupper( $type ) . ' ' . \join( ' AND ', $conditions );
	}

	/**
	 * Builds ORDER BY.
	 */
	protected function build_order_by() {
		if ( \count( $this->_order_by ) === 0 ) {
			return '';
		}

		return 'ORDER BY ' . \join( ', ', $this->_order_by );
	}

	/**
	 * Builds LIMIT.
	 */
	protected function build_limit() {
		if ( ! \is_null( $this->_limit ) ) {
			return "LIMIT {$this->_limit}";
		}

		return '';
	}

	/**
	 * Builds OFFSET.
	 */
	protected function build_offset() {
		if ( ! \is_null( $this->_offset ) ) {
			return 'OFFSET ' . $this->_offset;
		}

		return '';
	}

	/**
	 * Joins strings if they are not empty.
	 *
	 * @param string   $glue   Glue.
	 * @param string[] $pieces Pieces to join.
	 *
	 * @return string
	 */
	protected function join_if_not_empty( $glue, $pieces ) {
		$filtered_pieces = [];
		foreach ( $pieces as $piece ) {
			if ( \is_string( $piece ) ) {
				$piece = \trim( $piece );
			}
			if ( ! empty( $piece ) ) {
				$filtered_pieces[] = $piece;
			}
		}

		return \join( $glue, $filtered_pieces );
	}

	/**
	 * Quotes a string that is used as an identifier (table names, column names etc).
	 * This method can also deal with dot-separated identifiers eg table.column.
	 *
	 * @param string|string[] $identifier One or more identifiers.
	 *
	 * @return string
	 */
	protected function quote_one_identifier( $identifier ) {
		$parts = \explode( '.', $identifier );
		$parts = \array_map( [ $this, 'quote_identifier_part' ], $parts );

		return \join( '.', $parts );
	}

	/**
	 * Quotes a string that is used as an identifier (table names, column names etc) or an array containing multiple
	 * identifiers. This method can also deal with dot-separated identifiers eg table.column.
	 *
	 * @param string|string[] $identifier One or more identifiers.
	 *
	 * @return string
	 */
	protected function quote_identifier( $identifier ) {
		if ( \is_array( $identifier ) ) {
			$result = \array_map( [ $this, 'quote_one_identifier' ], $identifier );

			return \join( ', ', $result );
		}
		else {
			return $this->quote_one_identifier( $identifier );
		}
	}

	/**
	 * Quotes a single part of an identifier, using the identifier quote character specified in the config
	 * (or autodetected).
	 *
	 * @param string $part The part to quote.
	 *
	 * @return string
	 */
	protected function quote_identifier_part( $part ) {
		if ( $part === '*' ) {
			return $part;
		}
		$quote_character = '`';

		// Double up any identifier quotes to escape them.
		return $quote_character . \str_replace( $quote_character, $quote_character . $quote_character, $part ) . $quote_character;
	}

	/**
	 * Executes the SELECT query that has been built up by chaining methods on this class.
	 * Return an array of rows as associative arrays.
	 *
	 * @return array|false The result rows. False if the query failed.
	 */
	protected function run() {
		global $wpdb;

		$query   = $this->build_select();
		$success = self::execute( $query, $this->_values );

		if ( $success === false ) {
			// If the query fails run the migrations and try again.
			// Action is intentionally undocumented and should not be used by third-parties.
			\do_action( '_yoast_run_migrations' );
			$success = self::execute( $query, $this->_values );
		}

		$this->reset_idiorm_state();

		if ( $success === false ) {
			return false;
		}

		$rows = [];
		foreach ( $wpdb->last_result as $row ) {
			$rows[] = \get_object_vars( $row );
		}

		return $rows;
	}

	/**
	 * Resets the Idiorm instance state.
	 */
	private function reset_idiorm_state() {
		$this->_values                       = [];
		$this->_result_columns               = [ '*' ];
		$this->_using_default_result_columns = true;
	}

	/**
	 * Returns the raw data wrapped by this ORM instance as an associative array. Column names may optionally be
	 * supplied as arguments, if so, only those keys will be returned.
	 *
	 * @return array Associative array of the raw data.
	 */
	public function as_array() {
		if ( \func_num_args() === 0 ) {
			return $this->_data;
		}
		$args = \func_get_args();

		return \array_intersect_key( $this->_data, \array_flip( $args ) );
	}

	/**
	 * Returns the value of a property of this object (database row) or null if not present.
	 *
	 * If a column-names array is passed, it will return a associative array with the value of each column or null if
	 * it is not present.
	 *
	 * @param string|array $key Key.
	 *
	 * @return array|mixed|null
	 */
	public function get( $key ) {
		if ( \is_array( $key ) ) {
			$result = [];
			foreach ( $key as $column ) {
				$result[ $column ] = isset( $this->_data[ $column ] ) ? $this->_data[ $column ] : null;
			}

			return $result;
		}
		else {
			return isset( $this->_data[ $key ] ) ? $this->_data[ $key ] : null;
		}
	}

	/**
	 * Returns the name of the column in the database table which contains the primary key ID of the row.
	 *
	 * @return string The primary key ID of the row.
	 */
	protected function get_id_column_name() {
		if ( ! \is_null( $this->_instance_id_column ) ) {
			return $this->_instance_id_column;
		}

		return 'id';
	}

	/**
	 * Gets the primary key ID of this object.
	 *
	 * @param bool $disallow_null Whether to allow null IDs.
	 *
	 * @throws \Exception Primary key ID contains null value(s).
	 * @throws \Exception Primary key ID missing from row or is null.
	 *
	 * @return array|mixed|null
	 */
	public function id( $disallow_null = false ) {
		$id = $this->get( $this->get_id_column_name() );
		if ( $disallow_null ) {
			if ( \is_array( $id ) ) {
				foreach ( $id as $id_part ) {
					if ( $id_part === null ) {
						throw new \Exception( 'Primary key ID contains null value(s)' );
					}
				}
			}
			else {
				if ( $id === null ) {
					throw new \Exception( 'Primary key ID missing from row or is null' );
				}
			}
		}

		return $id;
	}

	/**
	 * Sets a property to a particular value on this object.
	 *
	 * To set multiple properties at once, pass an associative array as the first parameter and leave out the second
	 * parameter. Flags the properties as 'dirty' so they will be saved to the database when save() is called.
	 *
	 * @param string|array $key   Key.
	 * @param string|null  $value Value.
	 *
	 * @return ORM
	 */
	public function set( $key, $value = null ) {
		return $this->set_orm_property( $key, $value );
	}

	/**
	 * Set a property to a particular value on this object as expression.
	 *
	 * To set multiple properties at once, pass an associative array as the first parameter and leave out the second
	 * parameter. Flags the properties as 'dirty' so they will be saved to the database when save() is called.
	 *
	 * @param string|array $key   Key.
	 * @param string|null  $value Value.
	 *
	 * @return ORM
	 */
	public function set_expr( $key, $value = null ) {
		return $this->set_orm_property( $key, $value, true );
	}

	/**
	 * Sets a property on the ORM object.
	 *
	 * @param string|array $key   Key.
	 * @param string|null  $value Value.
	 * @param bool         $expr  Expression.
	 *
	 * @return ORM
	 */
	protected function set_orm_property( $key, $value = null, $expr = false ) {
		if ( ! \is_array( $key ) ) {
			$key = [ $key => $value ];
		}
		foreach ( $key as $field => $value ) {
			$this->_data[ $field ]         = $value;
			$this->_dirty_fields[ $field ] = $value;
			if ( $expr === false && isset( $this->_expr_fields[ $field ] ) ) {
				unset( $this->_expr_fields[ $field ] );
			}
			else {
				if ( $expr === true ) {
					$this->_expr_fields[ $field ] = true;
				}
			}
		}

		return $this;
	}

	/**
	 * Checks whether the given field has been changed since this object was saved.
	 *
	 * @param mixed $key Key.
	 *
	 * @return bool
	 */
	public function is_dirty( $key ) {
		return \array_key_exists( $key, $this->_dirty_fields );
	}

	/**
	 * Checks whether the model was the result of a call to create() or not.
	 *
	 * @return bool
	 */
	public function is_new() {
		return $this->_is_new;
	}

	/**
	 * Saves any fields which have been modified on this object to the database.
	 *
	 * @throws \Exception Primary key ID contains null value(s).
	 * @throws \Exception Primary key ID missing from row or is null.
	 *
	 * @return bool True on success.
	 */
	public function save() {
		global $wpdb;

		// Remove any expression fields as they are already baked into the query.
		$values = \array_values( \array_diff_key( $this->_dirty_fields, $this->_expr_fields ) );
		if ( ! $this->_is_new ) {
			// UPDATE.
			// If there are no dirty values, do nothing.
			if ( empty( $values ) && empty( $this->_expr_fields ) ) {
				return true;
			}
			$query = \join( ' ', [ $this->build_update(), $this->add_id_column_conditions() ] );

			$id = $this->id( true );
			if ( \is_array( $id ) ) {
				$values = \array_merge( $values, \array_values( $id ) );
			}
			else {
				$values[] = $id;
			}
		}
		else {
			// INSERT.
			$query = $this->build_insert();
		}
		$success = self::execute( $query, $values );
		// If we've just inserted a new record, set the ID of this object.
		if ( $this->_is_new ) {
			$this->_is_new = false;
			if ( $this->count_null_id_columns() !== 0 ) {
				$column = $this->get_id_column_name();
				// If the primary key is compound, assign the last inserted id to the first column.
				if ( \is_array( $column ) ) {
					$column = \reset( $column );
				}
				// Explicitly cast to int to make dealing with Id's simpler.
				$this->_data[ $column ] = (int) $wpdb->insert_id;
			}
		}
		$this->_dirty_fields = [];
		$this->_expr_fields  = [];

		return $success;
	}

	/**
	 * Updates many records in the database.
	 *
	 * @return int|bool The number of rows changed if the query was succesful. False otherwise.
	 */
	public function update_many() {
		// Remove any expression fields as they are already baked into the query.
		$values = \array_values( \array_diff_key( $this->_dirty_fields, $this->_expr_fields ) );

		// UPDATE.
		// If there are no dirty values, do nothing.
		if ( empty( $values ) && empty( $this->_expr_fields ) ) {
			return true;
		}

		$query = $this->join_if_not_empty( ' ', [ $this->build_update(), $this->build_where() ] );

		$success             = self::execute( $query, \array_merge( $values, $this->_values ) );
		$this->_dirty_fields = [];
		$this->_expr_fields  = [];

		return $success;
	}

	/**
	 * Adds a WHERE clause for every column that belongs to the primary key.
	 *
	 * @return string The where part of the query.
	 */
	public function add_id_column_conditions() {
		$query[] = 'WHERE';
		$keys    = \is_array( $this->get_id_column_name() ) ? $this->get_id_column_name() : [ $this->get_id_column_name() ];
		$first   = true;
		foreach ( $keys as $key ) {
			if ( $first ) {
				$first = false;
			}
			else {
				$query[] = 'AND';
			}
			$query[] = $this->quote_identifier( $key );
			$query[] = '= %s';
		}

		return \join( ' ', $query );
	}

	/**
	 * Builds an UPDATE query.
	 *
	 * @return string The update query.
	 */
	protected function build_update() {
		$query      = [];
		$query[]    = "UPDATE {$this->quote_identifier($this->_table_name)} SET";
		$field_list = [];
		foreach ( $this->_dirty_fields as $key => $value ) {
			if ( ! \array_key_exists( $key, $this->_expr_fields ) ) {
				$value = ( $value === null ) ? 'NULL' : '%s';
			}
			$field_list[] = "{$this->quote_identifier($key)} = {$value}";
		}
		$query[] = \join( ', ', $field_list );

		return \join( ' ', $query );
	}

	/**
	 * Builds an INSERT query.
	 *
	 * @return string The insert query.
	 */
	protected function build_insert() {
		$query        = [];
		$query[]      = 'INSERT INTO';
		$query[]      = $this->quote_identifier( $this->_table_name );
		$field_list   = \array_map( [ $this, 'quote_identifier' ], \array_keys( $this->_dirty_fields ) );
		$query[]      = '(' . \join( ', ', $field_list ) . ')';
		$query[]      = 'VALUES';
		$placeholders = $this->create_placeholders( $this->_dirty_fields );
		$query[]      = "({$placeholders})";

		return \join( ' ', $query );
	}

	/**
	 * Deletes this record from the database.
	 *
	 * @throws \Exception Primary key ID contains null value(s).
	 * @throws \Exception Primary key ID missing from row or is null.
	 *
	 * @return string The delete query.
	 */
	public function delete() {
		$query = [ 'DELETE FROM', $this->quote_identifier( $this->_table_name ), $this->add_id_column_conditions() ];

		return self::execute( \join( ' ', $query ), \is_array( $this->id( true ) ) ? \array_values( $this->id( true ) ) : [ $this->id( true ) ] );
	}

	/**
	 * Deletes many records from the database.
	 *
	 * @return bool|int Response of wpdb::query.
	 */
	public function delete_many() {
		// Build and return the full DELETE statement by concatenating
		// the results of calling each separate builder method.
		$query = $this->join_if_not_empty(
			' ',
			[
				'DELETE FROM',
				$this->quote_identifier( $this->_table_name ),
				$this->build_where(),
			]
		);

		return self::execute( $query, $this->_values );
	}

	/*
	 * ---  ArrayAccess  ---
	 */

	/**
	 * Checks whether the data has the key.
	 *
	 * @param mixed $key Key.
	 *
	 * @return bool Whether the data has the key.
	 */
	public function offsetExists( $key ) {
		return \array_key_exists( $key, $this->_data );
	}

	/**
	 * Retrieves the value of the key.
	 *
	 * @param mixed $key Key.
	 *
	 * @return array|mixed|null The value.
	 */
	public function offsetGet( $key ) {
		return $this->get( $key );
	}

	/**
	 * Sets the value of the key.
	 *
	 * @param string|int $key   Key.
	 * @param mixed      $value Value.
	 */
	public function offsetSet( $key, $value ) {
		if ( \is_null( $key ) ) {
			return;
		}
		$this->set( $key, $value );
	}

	/**
	 * Removes the given key from the data.
	 *
	 * @param mixed $key Key.
	 */
	public function offsetUnset( $key ) {
		unset( $this->_data[ $key ] );
		unset( $this->_dirty_fields[ $key ] );
	}

	/*
	 * --- MAGIC METHODS ---
	 */

	/**
	 * Handles magic get via offset.
	 *
	 * @param mixed $key Key.
	 *
	 * @return array|mixed|null The value in the offset.
	 */
	public function __get( $key ) {
		return $this->offsetGet( $key );
	}

	/**
	 * Handles magic set via offset.
	 *
	 * @param string|int $key   Key.
	 * @param mixed      $value Value.
	 */
	public function __set( $key, $value ) {
		$this->offsetSet( $key, $value );
	}

	/**
	 * Handles magic unset via offset.
	 *
	 * @param mixed $key Key.
	 */
	public function __unset( $key ) {
		$this->offsetUnset( $key );
	}

	/**
	 * Handles magic isset via offset.
	 *
	 * @param mixed $key Key.
	 *
	 * @return bool Whether the offset has the key.
	 */
	public function __isset( $key ) {
		return $this->offsetExists( $key );
	}
}