Class yii\db\Query

All Classes | Properties | Methods

Inheritance	yii\db\Query » yii\base\Component » yii\base\Object
Implements	yii\base\Configurable, yii\db\QueryInterface
Uses Traits	yii\db\QueryTrait
Subclasses	backend\modules\corsi\models\RisultatiInnovazionePrevalenteQuery, common\models\ItaliaComuniQuery, common\models\ItaliaProvinceQuery, common\models\ItaliaRegioniQuery, lispa\amos\chat\models\search\ConversationQuery, lispa\amos\chat\models\search\MessageQuery, lispa\amos\core\record\CachedActiveQuery, lispa\amos\core\record\CachedQuery, lispa\amos\cwh\models\query\CwhNodiQuery, lispa\amos\cwh\models\query\CwhRegolePubblicazioneQuery, lispa\amos\cwh\query\CwhActiveQuery, lispa\amos\inforeq\models\InforeqArgomentiQuery, lispa\amos\inforeq\models\InforeqQuery, lispa\amos\risultati\models\BisognoPerSviluppoRisultatiQuery, lispa\amos\risultati\models\ProtezioneInnovazioneRisultatiQuery, lispa\amos\risultati\models\RisultatiBisognoPerSviluppoRisultatiMmQuery, lispa\amos\risultati\models\RisultatiProtezioneInnovazioneRisultatiMmQuery, lispa\amos\risultati\models\RisultatiQuery, lispa\amos\risultati\models\RisultatiStadioSviluppoRisultatiMmQuery, lispa\amos\risultati\models\RisultatiTecnologieRisultatiMmQuery, lispa\amos\risultati\models\StadioSviluppoRisultatiQuery, lispa\amos\risultati\models\TecnologieRisultatiQuery, lispa\amos\slideshow\models\SlideshowQuery, lispa\amos\slideshow\models\SlideshowRouteQuery, lispa\amos\tag\models\search\TagQuery, yii\db\ActiveQuery
Available since version	2.0
Source Code	https://github.com/yiisoft/yii2/blob/master/framework/db/Query.php

Query represents a SELECT SQL statement in a way that is independent of DBMS.

Query provides a set of methods to facilitate the specification of different clauses in a SELECT statement. These methods can be chained together.

By calling createCommand(), we can get a yii\db\Command instance which can be further used to perform/execute the DB query against a database.

For example,

$query = new Query;
// compose the query
$query->select('id, name')
    ->from('user')
    ->limit(10);
// build and execute the query
$rows = $query->all();
// alternatively, you can create DB command and execute it
$command = $query->createCommand();
// $command->sql returns the actual SQL
$rows = $command->queryAll();

Query internally uses the yii\db\QueryBuilder class to generate the SQL statement.

A more detailed usage guide on how to work with Query can be found in the guide article on Query Builder.

Public Properties

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Property	Type	Description	Defined By
$behaviors	yii\base\Behavior[]	List of behaviors attached to this component	yii\base\Component
$distinct	boolean	Whether to select distinct rows of data only.	yii\db\Query
$emulateExecution	boolean	Whether to emulate the actual query execution, returning empty or false results.	yii\db\QueryTrait
$from	array	The table(s) to be selected from.	yii\db\Query
$groupBy	array	How to group the query results.	yii\db\Query
$having	string\|array\|yii\db\Expression	The condition to be applied in the GROUP BY clause.	yii\db\Query
$indexBy	string\|callable	The name of the column by which the query results should be indexed by.	yii\db\QueryTrait
$join	array	How to join with other tables.	yii\db\Query
$limit	integer\|yii\db\Expression	Maximum number of records to be returned.	yii\db\QueryTrait
$offset	integer\|yii\db\Expression	Zero-based offset from where the records are to be returned.	yii\db\QueryTrait
$orderBy	array	How to sort the query results.	yii\db\QueryTrait
$params	array	List of query parameter values indexed by parameter placeholders.	yii\db\Query
$select	array	The columns being selected.	yii\db\Query
$selectOption	string	Additional option that should be appended to the 'SELECT' keyword.	yii\db\Query
$union	array	This is used to construct the UNION clause(s) in a SQL statement.	yii\db\Query
$where	string\|array	Query condition.	yii\db\QueryTrait

Public Methods

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Method	Description	Defined By
__call()	Calls the named method which is not a class method.	yii\base\Component
__clone()	This method is called after the object is created by cloning an existing one.	yii\base\Component
__construct()	Constructor.	yii\base\Object
__get()	Returns the value of a component property.	yii\base\Component
__isset()	Checks if a property is set, i.e. defined and not null.	yii\base\Component
__set()	Sets the value of a component property.	yii\base\Component
__unset()	Sets a component property to be null.	yii\base\Component
addGroupBy()	Adds additional group-by columns to the existing ones.	yii\db\Query
addOrderBy()	Adds additional ORDER BY columns to the query.	yii\db\QueryTrait
addParams()	Adds additional parameters to be bound to the query.	yii\db\Query
addSelect()	Add more columns to the SELECT part of the query.	yii\db\Query
all()	Executes the query and returns all results as an array.	yii\db\Query
andFilterCompare()	Adds a filtering condition for a specific column and allow the user to choose a filter operator.	yii\db\Query
andFilterHaving()	Adds an additional HAVING condition to the existing one but ignores empty operands.	yii\db\Query
andFilterWhere()	Adds an additional WHERE condition to the existing one but ignores empty operands.	yii\db\QueryTrait
andHaving()	Adds an additional HAVING condition to the existing one.	yii\db\Query
andWhere()	Adds an additional WHERE condition to the existing one.	yii\db\Query
attachBehavior()	Attaches a behavior to this component.	yii\base\Component
attachBehaviors()	Attaches a list of behaviors to the component.	yii\base\Component
average()	Returns the average of the specified column values.	yii\db\Query
batch()	Starts a batch query.	yii\db\Query
behaviors()	Returns a list of behaviors that this component should behave as.	yii\base\Component
canGetProperty()	Returns a value indicating whether a property can be read.	yii\base\Component
canSetProperty()	Returns a value indicating whether a property can be set.	yii\base\Component
className()	Returns the fully qualified name of this class.	yii\base\Object
column()	Executes the query and returns the first column of the result.	yii\db\Query
count()	Returns the number of records.	yii\db\Query
create()	Creates a new Query object and copies its property values from an existing one.	yii\db\Query
createCommand()	Creates a DB command that can be used to execute this query.	yii\db\Query
detachBehavior()	Detaches a behavior from the component.	yii\base\Component
detachBehaviors()	Detaches all behaviors from the component.	yii\base\Component
distinct()	Sets the value indicating whether to SELECT DISTINCT or not.	yii\db\Query
each()	Starts a batch query and retrieves data row by row.	yii\db\Query
emulateExecution()	Sets whether to emulate query execution, preventing any interaction with data storage.	yii\db\QueryTrait
ensureBehaviors()	Makes sure that the behaviors declared in behaviors() are attached to this component.	yii\base\Component
exists()	Returns a value indicating whether the query result contains any row of data.	yii\db\Query
filterHaving()	Sets the HAVING part of the query but ignores empty operands.	yii\db\Query
filterWhere()	Sets the WHERE part of the query but ignores empty operands.	yii\db\QueryTrait
from()	Sets the FROM part of the query.	yii\db\Query
getBehavior()	Returns the named behavior object.	yii\base\Component
getBehaviors()	Returns all behaviors attached to this component.	yii\base\Component
groupBy()	Sets the GROUP BY part of the query.	yii\db\Query
hasEventHandlers()	Returns a value indicating whether there is any handler attached to the named event.	yii\base\Component
hasMethod()	Returns a value indicating whether a method is defined.	yii\base\Component
hasProperty()	Returns a value indicating whether a property is defined for this component.	yii\base\Component
having()	Sets the HAVING part of the query.	yii\db\Query
indexBy()	Sets the indexBy() property.	yii\db\QueryTrait
init()	Initializes the object.	yii\base\Object
innerJoin()	Appends an INNER JOIN part to the query.	yii\db\Query
join()	Appends a JOIN part to the query.	yii\db\Query
leftJoin()	Appends a LEFT OUTER JOIN part to the query.	yii\db\Query
limit()	Sets the LIMIT part of the query.	yii\db\QueryTrait
max()	Returns the maximum of the specified column values.	yii\db\Query
min()	Returns the minimum of the specified column values.	yii\db\Query
off()	Detaches an existing event handler from this component.	yii\base\Component
offset()	Sets the OFFSET part of the query.	yii\db\QueryTrait
on()	Attaches an event handler to an event.	yii\base\Component
one()	Executes the query and returns a single row of result.	yii\db\Query
orFilterHaving()	Adds an additional HAVING condition to the existing one but ignores empty operands.	yii\db\Query
orFilterWhere()	Adds an additional WHERE condition to the existing one but ignores empty operands.	yii\db\QueryTrait
orHaving()	Adds an additional HAVING condition to the existing one.	yii\db\Query
orWhere()	Adds an additional WHERE condition to the existing one.	yii\db\Query
orderBy()	Sets the ORDER BY part of the query.	yii\db\QueryTrait
params()	Sets the parameters to be bound to the query.	yii\db\Query
populate()	Converts the raw query results into the format as specified by this query.	yii\db\Query
prepare()	Prepares for building SQL.	yii\db\Query
rightJoin()	Appends a RIGHT OUTER JOIN part to the query.	yii\db\Query
scalar()	Returns the query result as a scalar value.	yii\db\Query
select()	Sets the SELECT part of the query.	yii\db\Query
sum()	Returns the sum of the specified column values.	yii\db\Query
trigger()	Triggers an event.	yii\base\Component
union()	Appends a SQL statement using UNION operator.	yii\db\Query
where()	Sets the WHERE part of the query.	yii\db\Query

Protected Methods

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Method	Description	Defined By
filterCondition()	Removes empty operands from the given query condition.	yii\db\QueryTrait
isEmpty()	Returns a value indicating whether the give value is "empty".	yii\db\QueryTrait
normalizeOrderBy()	Normalizes format of ORDER BY data	yii\db\QueryTrait
queryScalar()	Queries a scalar value by setting select() first.	yii\db\Query

Property Details

$distinct public property

Whether to select distinct rows of data only. If this is set true, the SELECT clause would be changed to SELECT DISTINCT.

public boolean $distinct = null

$from public property

The table(s) to be selected from. For example, ['user', 'post']. This is used to construct the FROM clause in a SQL statement.

Method Details

addGroupBy() public method

Adds additional group-by columns to the existing ones.

public $this addGroupBy ( $columns )
$columns	string\|array	Additional columns to be grouped by. Columns can be specified in either a string (e.g. "id, name") or an array (e.g. ['id', 'name']). The method will automatically quote the column names unless a column contains some parenthesis (which means the column contains a DB expression). Note that if your group-by is an expression containing commas, you should always use an array to represent the group-by information. Otherwise, the method will not be able to correctly determine the group-by columns. Since version 2.0.7, an yii\db\Expression object can be passed to specify the GROUP BY part explicitly in plain SQL.
return	$this	The query object itself

public $this addParams ( $params )
$params	array	List of query parameter values indexed by parameter placeholders. For example, `[':name' => 'Dan', ':age' => 31]`.
return	$this	The query object itself

public $this addSelect ( $columns )
$columns	string\|array\|yii\db\Expression	The columns to add to the select. See select() for more details about the format of this parameter.
return	$this	The query object itself

public array all ( $db = null )
$db	yii\db\Connection	The database connection used to generate the SQL statement. If this parameter is not given, the `db` application component will be used.
return	array	The query results. If the query results in nothing, an empty array will be returned.

public $this andFilterCompare ( $name, $value, $defaultOperator = '=' )
$name	string	The column name.
$value	string	The column value optionally prepended with the comparison operator.
$defaultOperator	string	The operator to use, when no operator is given in `$value`. Defaults to `=`, performing an exact match.
return	$this	The query object itself

See also:

public $this andFilterHaving ( array $condition )
$condition	array	The new HAVING condition. Please refer to having() on how to specify this parameter.
return	$this	The query object itself

andHaving() public method

Adds an additional HAVING condition to the existing one.

The new condition and the existing one will be joined using the AND operator.

See also:

public $this andHaving ( $condition, $params = [] )
$condition	string\|array\|yii\db\Expression	The new HAVING condition. Please refer to where() on how to specify this parameter.
$params	array	The parameters (name => value) to be bound to the query.
return	$this	The query object itself

andWhere() public method

Adds an additional WHERE condition to the existing one.

The new condition and the existing one will be joined using the AND operator.

See also:

public $this andWhere ( $condition, $params = [] )
$condition	string\|array\|yii\db\Expression	The new WHERE condition. Please refer to where() on how to specify this parameter.
$params	array	The parameters (name => value) to be bound to the query.
return	$this	The query object itself

average() public method

Returns the average of the specified column values.

public mixed average ( $q, $db = null )
$q	string	The column name or expression. Make sure you properly quote column names in the expression.
$db	yii\db\Connection	The database connection used to generate the SQL statement. If this parameter is not given, the `db` application component will be used.
return	mixed	The average of the specified column values.

batch() public method

Starts a batch query.

A batch query supports fetching data in batches, which can keep the memory usage under a limit. This method will return a yii\db\BatchQueryResult object which implements the Iterator interface and can be traversed to retrieve the data in batches.

For example,

$query = (new Query)->from('user');
foreach ($query->batch() as $rows) {
    // $rows is an array of 100 or fewer rows from user table
}

public yii\db\BatchQueryResult batch ( $batchSize = 100, $db = null )
$batchSize	integer	The number of records to be fetched in each batch.
$db	yii\db\Connection	The database connection. If not set, the "db" application component will be used.
return	yii\db\BatchQueryResult	The batch query result. It implements the Iterator interface and can be traversed to retrieve the data in batches.

column() public method

Executes the query and returns the first column of the result.

public array column ( $db = null )
$db	yii\db\Connection	The database connection used to generate the SQL statement. If this parameter is not given, the `db` application component will be used.
return	array	The first column of the query result. An empty array is returned if the query results in nothing.

count() public method

Returns the number of records.

public integer\|string count ( $q = '*', $db = null )
$q	string	The COUNT expression. Defaults to '*'. Make sure you properly quote column names in the expression.
$db	yii\db\Connection	The database connection used to generate the SQL statement. If this parameter is not given (or null), the `db` application component will be used.
return	integer\|string	Number of records. The result may be a string depending on the underlying database engine and to support integer values higher than a 32bit PHP integer can handle.

create() public static method

Creates a new Query object and copies its property values from an existing one.

The properties being copies are the ones to be used by query builders.

public static yii\db\Query create ( $from )
$from	yii\db\Query	The source query object
return	yii\db\Query	The new Query object

createCommand() public method

Creates a DB command that can be used to execute this query.

public yii\db\Command createCommand ( $db = null )
$db	yii\db\Connection	The database connection used to generate the SQL statement. If this parameter is not given, the `db` application component will be used.
return	yii\db\Command	The created DB command instance.

distinct() public method

Sets the value indicating whether to SELECT DISTINCT or not.

public $this distinct ( $value = true )
$value	boolean	Whether to SELECT DISTINCT or not.
return	$this	The query object itself

each() public method

Starts a batch query and retrieves data row by row.

This method is similar to batch() except that in each iteration of the result, only one row of data is returned. For example,

$query = (new Query)->from('user');
foreach ($query->each() as $row) {
}

public yii\db\BatchQueryResult each ( $batchSize = 100, $db = null )
$batchSize	integer	The number of records to be fetched in each batch.
$db	yii\db\Connection	The database connection. If not set, the "db" application component will be used.
return	yii\db\BatchQueryResult	The batch query result. It implements the Iterator interface and can be traversed to retrieve the data in batches.

exists() public method

Returns a value indicating whether the query result contains any row of data.

public boolean exists ( $db = null )
$db	yii\db\Connection	The database connection used to generate the SQL statement. If this parameter is not given, the `db` application component will be used.
return	boolean	Whether the query result contains any row of data.

filterHaving() public method (available since version 2.0.11)

Sets the HAVING part of the query but ignores empty operands.

This method is similar to having(). The main difference is that this method will remove empty query operands. As a result, this method is best suited for building query conditions based on filter values entered by users.

The following code shows the difference between this method and having():

// HAVING `age`=:age
$query->filterHaving(['name' => null, 'age' => 20]);
// HAVING `age`=:age
$query->having(['age' => 20]);
// HAVING `name` IS NULL AND `age`=:age
$query->having(['name' => null, 'age' => 20]);

Note that unlike having(), you cannot pass binding parameters to this method.

See also:

public $this filterHaving ( array $condition )
$condition	array	The conditions that should be put in the HAVING part. See having() on how to specify this parameter.
return	$this	The query object itself

from() public method

Sets the FROM part of the query.

public $this from ( $tables )
$tables	string\|array	The table(s) to be selected from. This can be either a string (e.g. `'user'`) or an array (e.g. `['user', 'profile']`) specifying one or several table names. Table names can contain schema prefixes (e.g. `'public.user'`) and/or table aliases (e.g. `'user u'`). The method will automatically quote the table names unless it contains some parenthesis (which means the table is given as a sub-query or DB expression). When the tables are specified as an array, you may also use the array keys as the table aliases (if a table does not need alias, do not use a string key). Use a Query object to represent a sub-query. In this case, the corresponding array key will be used as the alias for the sub-query. Here are some examples: // SELECT * FROM `user` `u`, `profile`; $query = (new \yii\db\Query)->from(['u' => 'user', 'profile']); // SELECT * FROM (SELECT * FROM `user` WHERE `active` = 1) `activeusers`; $subquery = (new \yii\db\Query)->from('user')->where(['active' => true]) $query = (new \yii\db\Query)->from(['activeusers' => $subquery]); // subquery can also be a string with plain SQL wrapped in parenthesis // SELECT * FROM (SELECT * FROM `user` WHERE `active` = 1) `activeusers`; $subquery = "(SELECT * FROM `user` WHERE `active` = 1)"; $query = (new \yii\db\Query)->from(['activeusers' => $subquery]);
return	$this	The query object itself

groupBy() public method

Sets the GROUP BY part of the query.

public $this groupBy ( $columns )
$columns	string\|array\|yii\db\Expression	The columns to be grouped by. Columns can be specified in either a string (e.g. "id, name") or an array (e.g. ['id', 'name']). The method will automatically quote the column names unless a column contains some parenthesis (which means the column contains a DB expression). Note that if your group-by is an expression containing commas, you should always use an array to represent the group-by information. Otherwise, the method will not be able to correctly determine the group-by columns. Since version 2.0.7, an yii\db\Expression object can be passed to specify the GROUP BY part explicitly in plain SQL.
return	$this	The query object itself

See also:

public $this having ( $condition, $params = [] )
$condition	string\|array\|yii\db\Expression	The conditions to be put after HAVING. Please refer to where() on how to specify this parameter.
$params	array	The parameters (name => value) to be bound to the query.
return	$this	The query object itself

innerJoin() public method

Appends an INNER JOIN part to the query.

public $this innerJoin ( $table, $on = '', $params = [] )
$table	string\|array	The table to be joined. Use a string to represent the name of the table to be joined. The table name can contain a schema prefix (e.g. 'public.user') and/or table alias (e.g. 'user u'). The method will automatically quote the table name unless it contains some parenthesis (which means the table is given as a sub-query or DB expression). Use an array to represent joining with a sub-query. The array must contain only one element. The value must be a yii\db\Query object representing the sub-query while the corresponding key represents the alias for the sub-query.
$on	string\|array	The join condition that should appear in the ON part. Please refer to join() on how to specify this parameter.
$params	array	The parameters (name => value) to be bound to the query.
return	$this	The query object itself

join() public method

Appends a JOIN part to the query.

The first parameter specifies what type of join it is.

public $this join ( $type, $table, $on = '', $params = [] )
$type	string	The type of join, such as INNER JOIN, LEFT JOIN.
$table	string\|array	The table to be joined. Use a string to represent the name of the table to be joined. The table name can contain a schema prefix (e.g. 'public.user') and/or table alias (e.g. 'user u'). The method will automatically quote the table name unless it contains some parenthesis (which means the table is given as a sub-query or DB expression). Use an array to represent joining with a sub-query. The array must contain only one element. The value must be a yii\db\Query object representing the sub-query while the corresponding key represents the alias for the sub-query.
$on	string\|array	The join condition that should appear in the ON part. Please refer to where() on how to specify this parameter. Note that the array format of where() is designed to match columns to values instead of columns to columns, so the following would not work as expected: `['post.author_id' => 'user.id']`, it would match the `post.author_id` column value against the string `'user.id'`. It is recommended to use the string syntax here which is more suited for a join: `'post.author_id = user.id'`
$params	array	The parameters (name => value) to be bound to the query.
return	$this	The query object itself

leftJoin() public method

Appends a LEFT OUTER JOIN part to the query.

public $this leftJoin ( $table, $on = '', $params = [] )
$table	string\|array	The table to be joined. Use a string to represent the name of the table to be joined. The table name can contain a schema prefix (e.g. 'public.user') and/or table alias (e.g. 'user u'). The method will automatically quote the table name unless it contains some parenthesis (which means the table is given as a sub-query or DB expression). Use an array to represent joining with a sub-query. The array must contain only one element. The value must be a yii\db\Query object representing the sub-query while the corresponding key represents the alias for the sub-query.
$on	string\|array	The join condition that should appear in the ON part. Please refer to join() on how to specify this parameter.
$params	array	The parameters (name => value) to be bound to the query
return	$this	The query object itself

max() public method

Returns the maximum of the specified column values.

public mixed max ( $q, $db = null )
$q	string	The column name or expression. Make sure you properly quote column names in the expression.
$db	yii\db\Connection	The database connection used to generate the SQL statement. If this parameter is not given, the `db` application component will be used.
return	mixed	The maximum of the specified column values.

min() public method

Returns the minimum of the specified column values.

public mixed min ( $q, $db = null )
$q	string	The column name or expression. Make sure you properly quote column names in the expression.
$db	yii\db\Connection	The database connection used to generate the SQL statement. If this parameter is not given, the `db` application component will be used.
return	mixed	The minimum of the specified column values.

one() public method

Executes the query and returns a single row of result.

public array\|boolean one ( $db = null )
$db	yii\db\Connection	The database connection used to generate the SQL statement. If this parameter is not given, the `db` application component will be used.
return	array\|boolean	The first row (in terms of an array) of the query result. False is returned if the query results in nothing.

orFilterHaving() public method (available since version 2.0.11)

Adds an additional HAVING condition to the existing one but ignores empty operands.

The new condition and the existing one will be joined using the OR operator.

This method is similar to orHaving(). The main difference is that this method will remove empty query operands. As a result, this method is best suited for building query conditions based on filter values entered by users.

See also:

public $this orFilterHaving ( array $condition )
$condition	array	The new HAVING condition. Please refer to having() on how to specify this parameter.
return	$this	The query object itself

orHaving() public method

Adds an additional HAVING condition to the existing one.

The new condition and the existing one will be joined using the OR operator.

See also:

public $this orHaving ( $condition, $params = [] )
$condition	string\|array\|yii\db\Expression	The new HAVING condition. Please refer to where() on how to specify this parameter.
$params	array	The parameters (name => value) to be bound to the query.
return	$this	The query object itself

orWhere() public method

Adds an additional WHERE condition to the existing one.

The new condition and the existing one will be joined using the OR operator.

See also:

public $this orWhere ( $condition, $params = [] )
$condition	string\|array\|yii\db\Expression	The new WHERE condition. Please refer to where() on how to specify this parameter.
$params	array	The parameters (name => value) to be bound to the query.
return	$this	The query object itself

params() public method

Sets the parameters to be bound to the query.

See also addParams().

public $this params ( $params )
$params	array	List of query parameter values indexed by parameter placeholders. For example, `[':name' => 'Dan', ':age' => 31]`.
return	$this	The query object itself

populate() public method

Converts the raw query results into the format as specified by this query.

This method is internally used to convert the data fetched from database into the format as required by this query.

public array populate ( $rows )
$rows	array	The raw query result from database
return	array	The converted query result

prepare() public method

Prepares for building SQL.

This method is called by yii\db\QueryBuilder when it starts to build SQL from a query object. You may override this method to do some final preparation work when converting a query into a SQL statement.

public $this prepare ( $builder )
$builder	yii\db\QueryBuilder
return	$this	A prepared query instance which will be used by yii\db\QueryBuilder to build the SQL

queryScalar() protected method

Queries a scalar value by setting select() first.

Restores the value of select to make this query reusable.

protected boolean\|string queryScalar ( $selectExpression, $db )
$selectExpression	string\|yii\db\Expression
$db	yii\db\Connection\|null

rightJoin() public method

Appends a RIGHT OUTER JOIN part to the query.

public $this rightJoin ( $table, $on = '', $params = [] )
$table	string\|array	The table to be joined. Use a string to represent the name of the table to be joined. The table name can contain a schema prefix (e.g. 'public.user') and/or table alias (e.g. 'user u'). The method will automatically quote the table name unless it contains some parenthesis (which means the table is given as a sub-query or DB expression). Use an array to represent joining with a sub-query. The array must contain only one element. The value must be a yii\db\Query object representing the sub-query while the corresponding key represents the alias for the sub-query.
$on	string\|array	The join condition that should appear in the ON part. Please refer to join() on how to specify this parameter.
$params	array	The parameters (name => value) to be bound to the query
return	$this	The query object itself

scalar() public method

Returns the query result as a scalar value.

The value returned will be the first column in the first row of the query results.

public string\|null\|false scalar ( $db = null )
$db	yii\db\Connection	The database connection used to generate the SQL statement. If this parameter is not given, the `db` application component will be used.
return	string\|null\|false	The value of the first column in the first row of the query result. False is returned if the query result is empty.

select() public method

Sets the SELECT part of the query.

public $this select ( $columns, $option = null )
$columns	string\|array\|yii\db\Expression	The columns to be selected. Columns can be specified in either a string (e.g. "id, name") or an array (e.g. ['id', 'name']). Columns can be prefixed with table names (e.g. "user.id") and/or contain column aliases (e.g. "user.id AS user_id"). The method will automatically quote the column names unless a column contains some parenthesis (which means the column contains a DB expression). A DB expression may also be passed in form of an yii\db\Expression object. Note that if you are selecting an expression like `CONCAT(first_name, ' ', last_name)`, you should use an array to specify the columns. Otherwise, the expression may be incorrectly split into several parts. When the columns are specified as an array, you may also use array keys as the column aliases (if a column does not need alias, do not use a string key). Starting from version 2.0.1, you may also select sub-queries as columns by specifying each such column as a `Query` instance representing the sub-query.
$option	string	Additional option that should be appended to the 'SELECT' keyword. For example, in MySQL, the option 'SQL_CALC_FOUND_ROWS' can be used.
return	$this	The query object itself

sum() public method

Returns the sum of the specified column values.

public mixed sum ( $q, $db = null )
$q	string	The column name or expression. Make sure you properly quote column names in the expression.
$db	yii\db\Connection	The database connection used to generate the SQL statement. If this parameter is not given, the `db` application component will be used.
return	mixed	The sum of the specified column values.

union() public method

Appends a SQL statement using UNION operator.

public $this union ( $sql, $all = false )
$sql	string\|yii\db\Query	The SQL statement to be appended using UNION
$all	boolean	TRUE if using UNION ALL and FALSE if using UNION
return	$this	The query object itself

where() public method

Sets the WHERE part of the query.

The method requires a $condition parameter, and optionally a $params parameter specifying the values to be bound to the query.

The $condition parameter should be either a string (e.g. 'id=1') or an array.

The $condition specified as an array can be in one of the following two formats:

hash format: ['column1' => value1, 'column2' => value2, ...]
operator format: [operator, operand1, operand2, ...]

A condition in hash format represents the following SQL expression in general: column1=value1 AND column2=value2 AND .... In case when a value is an array, an IN expression will be generated. And if a value is null, IS NULL will be used in the generated expression. Below are some examples:

['type' => 1, 'status' => 2] generates (type = 1) AND (status = 2).
['id' => [1, 2, 3], 'status' => 2] generates (id IN (1, 2, 3)) AND (status = 2).
['status' => null] generates status IS NULL.

A condition in operator format generates the SQL expression according to the specified operator, which can be one of the following:

and: the operands should be concatenated together using AND. For example, ['and', 'id=1', 'id=2'] will generate id=1 AND id=2. If an operand is an array, it will be converted into a string using the rules described here. For example, ['and', 'type=1', ['or', 'id=1', 'id=2']] will generate type=1 AND (id=1 OR id=2). The method will not do any quoting or escaping.
or: similar to the and operator except that the operands are concatenated using OR. For example, ['or', ['type' => [7, 8, 9]], ['id' => [1, 2, 3]]] will generate (type IN (7, 8, 9) OR (id IN (1, 2, 3))).
not: this will take only one operand and build the negation of it by prefixing the query string with NOT. For example ['not', ['attribute' => null]] will result in the condition NOT (attribute IS NULL).
between: operand 1 should be the column name, and operand 2 and 3 should be the starting and ending values of the range that the column is in. For example, ['between', 'id', 1, 10] will generate id BETWEEN 1 AND 10.
not between: similar to between except the BETWEEN is replaced with NOT BETWEEN in the generated condition.
in: operand 1 should be a column or DB expression, and operand 2 be an array representing the range of the values that the column or DB expression should be in. For example, ['in', 'id', [1, 2, 3]] will generate id IN (1, 2, 3). The method will properly quote the column name and escape values in the range.

To create a composite IN condition you can use and array for the column name and value, where the values are indexed by the column name: ['in', ['id', 'name'], [['id' => 1, 'name' => 'foo'], ['id' => 2, 'name' => 'bar']] ].

You may also specify a sub-query that is used to get the values for the IN-condition: ['in', 'user_id', (new Query())->select('id')->from('users')->where(['active' => 1])]
not in: similar to the in operator except that IN is replaced with NOT IN in the generated condition.
like: operand 1 should be a column or DB expression, and operand 2 be a string or an array representing the values that the column or DB expression should be like. For example, ['like', 'name', 'tester'] will generate name LIKE '%tester%'. When the value range is given as an array, multiple LIKE predicates will be generated and concatenated using AND. For example, ['like', 'name', ['test', 'sample']] will generate name LIKE '%test%' AND name LIKE '%sample%'. The method will properly quote the column name and escape special characters in the values. Sometimes, you may want to add the percentage characters to the matching value by yourself, you may supply a third operand false to do so. For example, ['like', 'name', '%tester', false] will generate name LIKE '%tester'.
or like: similar to the like operator except that OR is used to concatenate the LIKE predicates when operand 2 is an array.
not like: similar to the like operator except that LIKE is replaced with NOT LIKE in the generated condition.
or not like: similar to the not like operator except that OR is used to concatenate the NOT LIKE predicates.
exists: operand 1 is a query object that used to build an EXISTS condition. For example ['exists', (new Query())->select('id')->from('users')->where(['active' => 1])] will result in the following SQL expression: EXISTS (SELECT "id" FROM "users" WHERE "active"=1).
not exists: similar to the exists operator except that EXISTS is replaced with NOT EXISTS in the generated condition.
Additionally you can specify arbitrary operators as follows: A condition of ['>=', 'id', 10] will result in the following SQL expression: id >= 10.

See also:

public $this where ( $condition, $params = [] )
$condition	string\|array\|yii\db\Expression	The conditions that should be put in the WHERE part.
$params	array	The parameters (name => value) to be bound to the query.
return	$this	The query object itself

protected boolean\|string queryScalar ( $selectExpression, $db )
$selectExpression	string\|yii\db\Expression
$db	yii\db\Connection\|null