# BatchQueryResult > BatchQueryResult represents a batch query from which you can retrieve data in batches. [API reference](/docs/api/index.md) › [yii](/docs/api/yii/index.md) › [db](/docs/api/yii/db/index.md) › BatchQueryResult | class | `yii\db\BatchQueryResult` | | --- | --- | | Extends | [`yii\base\Component`](/docs/api/yii/base/component/index.md) » [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) | | Implements | [`Iterator`](https://www.php.net/manual/en/class.iterator.php), [`yii\base\Configurable`](/docs/api/yii/base/configurable/index.md) | | Since | 2.0 | | Source | [`framework/db/BatchQueryResult.php`](https://github.com/yiisoft/yii2/blob/22.0/framework/db/BatchQueryResult.php#L36) | BatchQueryResult represents a batch query from which you can retrieve data in batches. You usually do not instantiate BatchQueryResult directly. Instead, you obtain it by calling [`Query::batch()`](/docs/api/yii/db/query/index.md#method-batch) or [`Query::each()`](/docs/api/yii/db/query/index.md#method-each). Because BatchQueryResult implements the [`Iterator`](https://www.php.net/manual/en/class.iterator.php) interface, you can iterate it to obtain a batch of data in each iteration. For example, ``` $query = (new Query)->from('user'); foreach ($query->batch() as $i => $users) { // $users represents the rows in the $i-th batch } foreach ($query->each() as $user) { } ``` ## Properties | Property | Type | Description | Defined by | | --- | --- | --- | --- | | `$batchSize` | `int` | The number of rows to be returned in each batch. Default: `100`. | `BatchQueryResult` | | [`$behaviors`](/docs/api/yii/base/component/index.md#property-behaviors) read-only | `array<`[`yii\base\Behavior`](/docs/api/yii/base/behavior/index.md)`>` | List of behaviors attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`$db`](#property-db) | [`Connection`](/docs/api/yii/db/connection/index.md)`\|null` | The DB connection to be used when performing batch query. Default: `null`. | `BatchQueryResult` | | [`$each`](#property-each) | `bool` | Whether to return a single row during each iteration. Default: `false`. | `BatchQueryResult` | | [`$query`](#property-query) | [`Query`](/docs/api/yii/db/query/index.md) | The query object associated with this batch query. Default: `null`. | `BatchQueryResult` | ## Methods | Method | Description | Defined by | | --- | --- | --- | | [`__construct()`](/docs/api/yii/base/baseobject/index.md#method-__construct) | Constructor. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) | | [`__call()`](/docs/api/yii/base/component/index.md#method-__call) | Calls the named method which is not a class method. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`__clone()`](/docs/api/yii/base/component/index.md#method-__clone) | This method is called after the object is created by cloning an existing one. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`__destruct()`](#method-__destruct) | Destructor. | `BatchQueryResult` | | [`__get()`](/docs/api/yii/base/component/index.md#method-__get) | Returns the value of a component property. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`__isset()`](/docs/api/yii/base/component/index.md#method-__isset) | Checks if a property is set, i.e. defined and not null. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`__set()`](/docs/api/yii/base/component/index.md#method-__set) | Sets the value of a component property. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`__unset()`](/docs/api/yii/base/component/index.md#method-__unset) | Sets a component property to be null. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`__wakeup()`](#method-__wakeup) | Unserialization is disabled to prevent remote code execution in case application calls unserialize() on user input containing specially crafted string. | `BatchQueryResult` | | [`attachBehavior()`](/docs/api/yii/base/component/index.md#method-attachBehavior) | Attaches a behavior to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`attachBehaviors()`](/docs/api/yii/base/component/index.md#method-attachBehaviors) | Attaches a list of behaviors to the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`behaviors()`](/docs/api/yii/base/component/index.md#method-behaviors) | Returns a list of behaviors that this component should behave as. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`canGetProperty()`](/docs/api/yii/base/component/index.md#method-canGetProperty) | Returns a value indicating whether a property can be read. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`canSetProperty()`](/docs/api/yii/base/component/index.md#method-canSetProperty) | Returns a value indicating whether a property can be set. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`className()`](/docs/api/yii/base/baseobject/index.md#method-className) static | Returns the fully qualified name of this class. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) | | [`current()`](#method-current) | Returns the current dataset. | `BatchQueryResult` | | [`detachBehavior()`](/docs/api/yii/base/component/index.md#method-detachBehavior) | Detaches a behavior from the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`detachBehaviors()`](/docs/api/yii/base/component/index.md#method-detachBehaviors) | Detaches all behaviors from the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`ensureBehaviors()`](/docs/api/yii/base/component/index.md#method-ensureBehaviors) | Makes sure that the behaviors declared in [`behaviors()`](/docs/api/yii/base/component/index.md#method-behaviors) are attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`getBehavior()`](/docs/api/yii/base/component/index.md#method-getBehavior) | Returns the named behavior object. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`getBehaviors()`](/docs/api/yii/base/component/index.md#method-getBehaviors) | Returns all behaviors attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`hasEventHandlers()`](/docs/api/yii/base/component/index.md#method-hasEventHandlers) | Returns a value indicating whether there is any handler attached to the named event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`hasMethod()`](/docs/api/yii/base/component/index.md#method-hasMethod) | Returns a value indicating whether a method is defined. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`hasProperty()`](/docs/api/yii/base/component/index.md#method-hasProperty) | Returns a value indicating whether a property is defined for this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`init()`](/docs/api/yii/base/baseobject/index.md#method-init) | Initializes the object. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) | | [`key()`](#method-key) | Returns the index of the current dataset. | `BatchQueryResult` | | [`next()`](#method-next) | Moves the internal pointer to the next dataset. | `BatchQueryResult` | | [`off()`](/docs/api/yii/base/component/index.md#method-off) | Detaches an existing event handler from this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`on()`](/docs/api/yii/base/component/index.md#method-on) | Attaches an event handler to an event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`reset()`](#method-reset) | Resets the batch query. | `BatchQueryResult` | | [`rewind()`](#method-rewind) | Resets the iterator to the initial state. | `BatchQueryResult` | | [`trigger()`](/docs/api/yii/base/component/index.md#method-trigger) | Triggers an event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) | | [`valid()`](#method-valid) | Returns whether there is a valid dataset at the current position. | `BatchQueryResult` | | [`fetchData()`](#method-fetchData) protected | Fetches the next batch of data. | `BatchQueryResult` | | [`getRows()`](#method-getRows) protected | Reads and collects rows for batch | `BatchQueryResult` | ## Events | Event | Type | Description | Defined by | | --- | --- | --- | --- | | `EVENT_RESET` | `yii\db\Event` | An event that is triggered when the batch query is reset. Event name: `'reset'`. Available since 2.0.41. | `BatchQueryResult` | | `EVENT_FINISH` | `yii\db\Event` | An event that is triggered when the last batch has been fetched. Event name: `'finish'`. Available since 2.0.41. | `BatchQueryResult` | ## Constants | Constant | Value | Description | Defined by | | --- | --- | --- | --- | | `MSSQL_NO_MORE_ROWS_ERROR_CODE` | `-13` | MSSQL error code for exception that is thrown when last batch is size less than specified batch size | `BatchQueryResult` | ## Property details ### $db ```php public yii\db\Connection|null $db = null ``` The DB connection to be used when performing batch query. If null, the "db" application component will be used. ### $each ```php public bool $each = false ``` Whether to return a single row during each iteration. If false, a whole batch of rows will be returned in each iteration. ### $query ```php public yii\db\Query $query = null ``` The query object associated with this batch query. Do not modify this property directly unless after [`reset()`](/docs/api/yii/db/batchqueryresult/index.md#method-reset) is called explicitly. ## Method details ### __destruct() ```php public function __destruct(): mixed ``` Destructor. **Returns** `mixed` ### __wakeup() ```php public function __wakeup(): mixed ``` Unserialization is disabled to prevent remote code execution in case application calls unserialize() on user input containing specially crafted string. **Returns** `mixed` **Since** 2.0.38 **See also** - ### current() ```php public function current(): yii\db\TValue ``` Returns the current dataset. This method is required by the interface [`Iterator`](https://www.php.net/manual/en/class.iterator.php). **Returns** `yii\db\TValue`: The current dataset. ### key() ```php public function key(): yii\db\TKey|null ``` Returns the index of the current dataset. This method is required by the interface [`Iterator`](https://www.php.net/manual/en/class.iterator.php). **Returns** `yii\db\TKey|null`: The index of the current row. ### next() ```php public function next(): mixed ``` Moves the internal pointer to the next dataset. This method is required by the interface [`Iterator`](https://www.php.net/manual/en/class.iterator.php). **Returns** `mixed` ### reset() ```php public function reset(): mixed ``` Resets the batch query. This method will clean up the existing batch query so that a new batch query can be performed. **Returns** `mixed` ### rewind() ```php public function rewind(): mixed ``` Resets the iterator to the initial state. This method is required by the interface [`Iterator`](https://www.php.net/manual/en/class.iterator.php). **Returns** `mixed` ### valid() ```php public function valid(): bool ``` Returns whether there is a valid dataset at the current position. This method is required by the interface [`Iterator`](https://www.php.net/manual/en/class.iterator.php). **Returns** `bool`: Whether there is a valid dataset at the current position. ### fetchData() ```php protected function fetchData(): array ``` Fetches the next batch of data. **Returns** `array`: The data fetched **Throws** - [`Exception`](/docs/api/yii/db/exception/index.md) ### getRows() ```php protected function getRows(): array ``` Reads and collects rows for batch **Returns** `array` **Since** 2.0.23