# Class yii\db\Connection

Inheritance | yii\db\Connection » yii\base\Component » yii\base\BaseObject
Implements | yii\base\Configurable
Subclasses | yii\sphinx\Connection
Available since version | 2.0
Source Code | https://github.com/yiisoft/yii2/blob/master/framework/db/Connection.php

Connection represents a connection to a database via PDO.

Connection works together with yii\db\Command, yii\db\DataReader and yii\db\Transaction to provide data access to various DBMS in a common set of APIs. They are a thin wrapper of the PDO PHP extension.

Connection supports database replication and read-write splitting. In particular, a Connection component can be configured with multiple $masters and $slaves. It will do load balancing and failover by choosing appropriate servers. It will also automatically direct read operations to the slaves and write operations to the masters.

To establish a DB connection, set $dsn, $username and $password, and then call open() to connect to the database server. The current state of the connection can be checked using $isActive.

The following example shows how to create a Connection instance and establish the DB connection:

    $connection = new \yii\db\Connection([
        'dsn' => $dsn,
        'username' => $username,
        'password' => $password,
    ]);
    $connection->open();

After the DB connection is established, one can execute SQL statements like the following:

    $command = $connection->createCommand('SELECT * FROM post');
    $posts = $command->queryAll();
    $command = $connection->createCommand('UPDATE post SET status=1');
    $command->execute();

One can also do prepared SQL execution and bind parameters to the prepared SQL. When the parameters are coming from user input, you should use this approach to prevent SQL injection attacks. The following is an example:

    $command = $connection->createCommand('SELECT * FROM post WHERE id=:id');
    $command->bindValue(':id', $_GET['id']);
    $post = $command->query();

For more information about how to perform various DB queries, please refer to yii\db\Command.

If the underlying DBMS supports transactions, you can perform transactional SQL queries like the following:

    $transaction = $connection->beginTransaction();
    try {
        $connection->createCommand($sql1)->execute();
        $connection->createCommand($sql2)->execute();
        // ... executing other SQL statements ...
        $transaction->commit();
    } catch (Exception $e) {
        $transaction->rollBack();
    }

You also can use shortcut for the above like the following:

    $connection->transaction(function () {
        $order = new Order($customer);
        $order->save();
        $order->addItems($items);
    });

If needed you can pass transaction isolation level as a second parameter:

    $connection->transaction(function (Connection $db) {
        //return $db->...
    }, Transaction::READ_UNCOMMITTED);

Connection is often used as an application component and configured in the application configuration like the following:

    'components' => [
        'db' => [
            'class' => '\yii\db\Connection',
            'dsn' => 'mysql:host=127.0.0.1;dbname=demo',
            'username' => 'root',
            'password' => '',
            'charset' => 'utf8',
        ],
    ],

## Public Properties

Hide inherited properties

Property | Type | Description | Defined By
--- | --- | --- | ---
$attributes | array | PDO attributes (name => value) that should be set when calling open() to establish a DB connection. | yii\db\Connection
$behaviors | yii\base\Behavior[] | List of behaviors attached to this component. This property is read-only. | yii\base\Component
$charset | string | The charset used for database connection. | yii\db\Connection
$commandClass | string | The class used to create new database yii\db\Command objects. | yii\db\Connection
$commandMap | array | Mapping between PDO driver names and yii\db\Command classes. | yii\db\Connection
$driverName | string | Name of the DB driver. | yii\db\Connection
$dsn | string | The Data Source Name, or DSN, contains the information required to connect to the database. | yii\db\Connection
$emulatePrepare | boolean | Whether to turn on prepare emulation. | yii\db\Connection
$enableLogging | boolean | Whether to enable logging of database queries. | yii\db\Connection
$enableProfiling | boolean | Whether to enable profiling of opening database connection and database queries. | yii\db\Connection
$enableQueryCache | boolean | Whether to enable query caching. | yii\db\Connection
$enableSavepoint | boolean | Whether to enable [savepoint](http://en. | yii\db\Connection
$enableSchemaCache | boolean | Whether to enable schema caching. | yii\db\Connection
$enableSlaves | boolean | Whether to enable read/write splitting by using $slaves to read data. | yii\db\Connection
$isActive | boolean | Whether the DB connection is established. This property is read-only. | yii\db\Connection
$isSybase | boolean | If the database connected via pdo_dblib is SyBase. | yii\db\Connection
$lastInsertID | string | The row ID of the last row inserted, or the last value retrieved from the sequence object. This property is read-only. | yii\db\Connection
$master | yii\db\Connection | The currently active master connection. `null` is returned if there is no master available. This property is read-only. | yii\db\Connection
$masterConfig | array | The configuration that should be merged with every master configuration listed in $masters. | yii\db\Connection
$masterPdo | PDO | The PDO instance for the currently active master connection. This property is read-only. | yii\db\Connection
$masters | array | List of master connection configurations. | yii\db\Connection
$password | string | The password for establishing DB connection. | yii\db\Connection
$pdo | PDO | The PHP PDO instance associated with this DB connection. | yii\db\Connection
$pdoClass | string | Custom PDO wrapper class. | yii\db\Connection
$queryBuilder | yii\db\QueryBuilder | The query builder for the current DB connection. Note that the type of this property differs in getter and setter. See getQueryBuilder() and setQueryBuilder() for details. | yii\db\Connection
$queryCache | yii\caching\CacheInterface|string | The cache object or the ID of the cache application component that is used for query caching. | yii\db\Connection
$queryCacheDuration | integer | The default number of seconds that query results can remain valid in cache. | yii\db\Connection
$schema | yii\db\Schema | The schema information for the database opened by this connection. This property is read-only. | yii\db\Connection
$schemaCache | yii\caching\CacheInterface|string | The cache object or the ID of the cache application component that is used to cache the table metadata. | yii\db\Connection
$schemaCacheDuration | integer | Number of seconds that table metadata can remain valid in cache. | yii\db\Connection
$schemaCacheExclude | array | List of tables whose metadata should NOT be cached. | yii\db\Connection
$schemaMap | array | Mapping between PDO driver names and yii\db\Schema classes. | yii\db\Connection
$serverRetryInterval | integer | The retry interval in seconds for dead servers listed in $masters and $slaves. | yii\db\Connection
$serverStatusCache | yii\caching\CacheInterface|string|false | The cache object or the ID of the cache application component that is used to store the health status of the DB servers specified in $masters and $slaves. | yii\db\Connection
$serverVersion | string | Server version as a string. This property is read-only. | yii\db\Connection
$shuffleMasters | boolean | Whether to shuffle $masters before getting one. | yii\db\Connection
$slave | yii\db\Connection | The currently active slave connection. `null` is returned if there is no slave available and `$fallbackToMaster` is false. This property is read-only. | yii\db\Connection
$slaveConfig | array | The configuration that should be merged with every slave configuration listed in $slaves. | yii\db\Connection
$slavePdo | PDO | The PDO instance for the currently active slave connection. `null` is returned if no slave connection is available and `$fallbackToMaster` is false. This property is read-only. | yii\db\Connection
$slaves | array | List of slave connection configurations. | yii\db\Connection
$tablePrefix | string | The common prefix or suffix for table names. | yii\db\Connection
$transaction | yii\db\Transaction|null | The currently active transaction. Null if no active transaction. This property is read-only. | yii\db\Connection
$username | string | The username for establishing DB connection. | yii\db\Connection

## Public Methods

Hide inherited methods

Method | Description | Defined By
--- | --- | ---
__call() | Calls the named method which is not a class method. | yii\base\Component
__clone() | Reset the connection after cloning. | yii\db\Connection
__construct() | Constructor. | yii\base\BaseObject
__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
__sleep() | Close the connection before serializing. | yii\db\Connection
__unset() | Sets a component property to be null. | yii\base\Component
attachBehavior() | Attaches a behavior to this component. | yii\base\Component
attachBehaviors() | Attaches a list of behaviors to the component. | yii\base\Component
beginTransaction() | Starts a transaction. | yii\db\Connection
behaviors() | Returns a list of behaviors that this component should behave as. | yii\base\Component
cache() | Uses query cache for the queries performed with the callable. | yii\db\Connection
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\BaseObject
close() | Closes the currently active DB connection. | yii\db\Connection
createCommand() | Creates a command for execution. | yii\db\Connection
detachBehavior() | Detaches a behavior from the component. | yii\base\Component
detachBehaviors() | Detaches all behaviors from the component. | yii\base\Component
ensureBehaviors() | Makes sure that the behaviors declared in behaviors() are attached to this component. | yii\base\Component
getBehavior() | Returns the named behavior object. | yii\base\Component
getBehaviors() | Returns all behaviors attached to this component. | yii\base\Component
getDriverName() | Returns the name of the DB driver. Based on the the current $dsn, in case it was not set explicitly by an end user. | yii\db\Connection
getIsActive() | Returns a value indicating whether the DB connection is established. | yii\db\Connection
getLastInsertID() | Returns the ID of the last inserted row or sequence value. | yii\db\Connection
getMaster() | Returns the currently active master connection. | yii\db\Connection
getMasterPdo() | Returns the PDO instance for the currently active master connection. | yii\db\Connection
getQueryBuilder() | Returns the query builder for the current DB connection. | yii\db\Connection
getQueryCacheInfo() | Returns the current query cache information. | yii\db\Connection
getSchema() | Returns the schema information for the database opened by this connection. | yii\db\Connection
getServerVersion() | Returns a server version as a string comparable by \version_compare(). | yii\db\Connection
getSlave() | Returns the currently active slave connection. | yii\db\Connection
getSlavePdo() | Returns the PDO instance for the currently active slave connection. | yii\db\Connection
getTableSchema() | Obtains the schema information for the named table. | yii\db\Connection
getTransaction() | Returns the currently active transaction. | yii\db\Connection
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
init() | Initializes the object. | yii\base\BaseObject
noCache() | Disables query cache temporarily. | yii\db\Connection
off() | Detaches an existing event handler from this component. | yii\base\Component
on() | Attaches an event handler to an event. | yii\base\Component
open() | Establishes a DB connection. | yii\db\Connection
quoteColumnName() | Quotes a column name for use in a query. | yii\db\Connection
quoteSql() | Processes a SQL statement by quoting table and column names that are enclosed within double brackets. | yii\db\Connection
quoteTableName() | Quotes a table name for use in a query. | yii\db\Connection
quoteValue() | Quotes a string value for use in a query. | yii\db\Connection
setDriverName() | Changes the current driver name. | yii\db\Connection
setQueryBuilder() | Can be used to set yii\db\QueryBuilder configuration via Connection configuration array. | yii\db\Connection
transaction() | Executes callback provided in a transaction. | yii\db\Connection
trigger() | Triggers an event. | yii\base\Component
useMaster() | Executes the provided callback by using the master connection. | yii\db\Connection

## Protected Methods

Hide inherited methods

Method | Description | Defined By
--- | --- | ---
createPdoInstance() | Creates the PDO instance. | yii\db\Connection
initConnection() | Initializes the DB connection. | yii\db\Connection
openFromPool() | Opens the connection to a server in the pool. | yii\db\Connection
openFromPoolSequentially() | Opens the connection to a server in the pool. | yii\db\Connection

## Events

Hide inherited events

Event | Type | Description | Defined By
--- | --- | --- | ---
EVENT_AFTER_OPEN | \yii\db\yii\base\Event | An event that is triggered after a DB connection is established | yii\db\Connection
EVENT_BEGIN_TRANSACTION | \yii\db\yii\base\Event | An event that is triggered right before a top-level transaction is started | yii\db\Connection
EVENT_COMMIT_TRANSACTION | \yii\db\yii\base\Event | An event that is triggered right after a top-level transaction is committed | yii\db\Connection
EVENT_ROLLBACK_TRANSACTION | \yii\db\yii\base\Event | An event that is triggered right after a top-level transaction is rolled back | yii\db\Connection

## Property Details

$attributes public property

PDO attributes (name => value) that should be set when calling open() to establish a DB connection. Please refer to the PHP manual for details about available attributes.

public array $attributes = null
$charset public property

The charset used for database connection. The property is only used for MySQL, PostgreSQL and CUBRID databases. Defaults to null, meaning using default charset as configured by the database.

For Oracle Database, the charset must be specified in the $dsn, for example for UTF-8 by appending `;charset=UTF-8` to the DSN string.

The same applies for if you're using GBK or BIG5 charset with MySQL, then it's highly recommended to specify charset via $dsn like `'mysql:dbname=mydatabase;host=127.0.0.1;charset=GBK;'`.

public string $charset = null
$commandClass public property (available since version 2.0.7)
Deprecated since 2.0.14. Use $commandMap for precise configuration.

The class used to create new database yii\db\Command objects. If you want to extend the yii\db\Command class, you may configure this property to use your extended version of the class. Since version 2.0.14 $commandMap is used if this property is set to its default value.

See also createCommand().

public string $commandClass = 'yii\db\Command'
$commandMap public property (available since version 2.0.14)

Mapping between PDO driver names and yii\db\Command classes. The keys of the array are PDO driver names while the values are either the corresponding command class names or configurations. Please refer to Yii::createObject() for details on how to specify a configuration.

This property is mainly used by createCommand() to create new database yii\db\Command objects. You normally do not need to set this property unless you want to use your own yii\db\Command class or support DBMS that is not supported by Yii.

public array $commandMap = ['pgsql' => 'yii\db\Command', 'mysqli' => 'yii\db\Command', 'mysql' => 'yii\db\Command', 'sqlite' => 'yii\db\sqlite\Command', 'sqlite2' => 'yii\db\sqlite\Command', 'sqlsrv' => 'yii\db\Command', 'oci' => 'yii\db\oci\Command', 'mssql' => 'yii\db\Command', 'dblib' => 'yii\db\Command', 'cubrid' => 'yii\db\Command']
$driverName public property

Name of the DB driver.

public string $driverName = null
$dsn public property

The Data Source Name, or DSN, contains the information required to connect to the database. Please refer to the PHP manual on the format of the DSN string.

For SQLite you may use a path alias for specifying the database path, e.g. `sqlite:@app/data/db.sql`.

See also $charset.

public string $dsn = null
$emulatePrepare public property

Whether to turn on prepare emulation. Defaults to false, meaning PDO will use the native prepare support if available. For some databases (such as MySQL), this may need to be set true so that PDO can emulate the prepare support to bypass the buggy native prepare support. The default value is null, which means the PDO ATTR_EMULATE_PREPARES value will not be changed.

public boolean $emulatePrepare = null
$enableLogging public property (available since version 2.0.12)

Whether to enable logging of database queries. Defaults to true. You may want to disable this option in a production environment to gain performance if you do not need the information being logged.

See also $enableProfiling.

public boolean $enableLogging = true
$enableProfiling public property (available since version 2.0.12)

Whether to enable profiling of opening database connection and database queries. Defaults to true. You may want to disable this option in a production environment to gain performance if you do not need the information being logged.

See also $enableLogging.

public boolean $enableProfiling = true
$enableQueryCache public property

Whether to enable query caching. Note that in order to enable query caching, a valid cache component as specified by $queryCache must be enabled and $enableQueryCache must be set true. Also, only the results of the queries enclosed within cache() will be cached.

See also:

- $queryCache
- cache()
- noCache()

public boolean $enableQueryCache = true
$enableSavepoint public property

Whether to enable savepoint. Note that if the underlying DBMS does not support savepoint, setting this property to be true will have no effect.

public boolean $enableSavepoint = true
$enableSchemaCache public property

Whether to enable schema caching. Note that in order to enable truly schema caching, a valid cache component as specified by $schemaCache must be enabled and $enableSchemaCache must be set true.

See also:

- $schemaCacheDuration
- $schemaCacheExclude
- $schemaCache

public boolean $enableSchemaCache = false
$enableSlaves public property

Whether to enable read/write splitting by using $slaves to read data. Note that if $slaves is empty, read/write splitting will NOT be enabled no matter what value this property takes.

public boolean $enableSlaves = true
$isActive public property

Whether the DB connection is established. This property is read-only.

public boolean $isActive = null
$isSybase public property (available since version 2.0.38)

If the database connected via pdo_dblib is SyBase.

public boolean $isSybase = false
$lastInsertID public property

The row ID of the last row inserted, or the last value retrieved from the sequence object. This property is read-only.

public string $lastInsertID = null
$master public property

The currently active master connection. `null` is returned if there is no master available. This property is read-only.

public yii\db\Connection $master = null
$masterConfig public property

The configuration that should be merged with every master configuration listed in $masters. For example,

    [
        'username' => 'master',
        'password' => 'master',
        'attributes' => [
            // use a smaller connection timeout
            PDO::ATTR_TIMEOUT => 10,
        ],
    ]

public array $masterConfig = []
$masterPdo public property

The PDO instance for the currently active master connection. This property is read-only.

public PDO $masterPdo = null
$masters public property

List of master connection configurations. Each configuration is used to create a master DB connection. When open() is called, one of these configurations will be chosen and used to create a DB connection which will be used by this object. Note that when this property is not empty, the connection setting (e.g. "dsn", "username") of this object will be ignored.

See also:

- $masterConfig
- $shuffleMasters

public array $masters = []
$password public property

The password for establishing DB connection. Defaults to `null` meaning no password to use.

public string $password = null
$pdo public property

The PHP PDO instance associated with this DB connection. This property is mainly managed by open() and close() methods. When a DB connection is active, this property will represent a PDO instance; otherwise, it will be null.

See also $pdoClass.

public PDO $pdo = null
$pdoClass public property

Custom PDO wrapper class. If not set, it will use PDO or yii\db\mssql\PDO when MSSQL is used.

See also $pdo.

public string $pdoClass = null
$queryBuilder public property

The query builder for the current DB connection. Note that the type of this property differs in getter and setter. See getQueryBuilder() and setQueryBuilder() for details.

public yii\db\QueryBuilder $queryBuilder = null
$queryCache public property

The cache object or the ID of the cache application component that is used for query caching.

See also $enableQueryCache.

public yii\caching\CacheInterface|string $queryCache = 'cache'
$queryCacheDuration public property

The default number of seconds that query results can remain valid in cache. Defaults to 3600, meaning 3600 seconds, or one hour. Use 0 to indicate that the cached data will never expire. The value of this property will be used when cache() is called without a cache duration.

See also:

- $enableQueryCache
- cache()

public integer $queryCacheDuration = 3600
$schema public property

The schema information for the database opened by this connection. This property is read-only.

public yii\db\Schema $schema = null
$schemaCache public property

The cache object or the ID of the cache application component that is used to cache the table metadata.

See also $enableSchemaCache.

public yii\caching\CacheInterface|string $schemaCache = 'cache'
$schemaCacheDuration public property

Number of seconds that table metadata can remain valid in cache. Use 0 to indicate that the cached data will never expire.

See also $enableSchemaCache.

public integer $schemaCacheDuration = 3600
$schemaCacheExclude public property

List of tables whose metadata should NOT be cached. Defaults to empty array. The table names may contain schema prefix, if any. Do not quote the table names.

See also $enableSchemaCache.

public array $schemaCacheExclude = []
$schemaMap public property

Mapping between PDO driver names and yii\db\Schema classes. The keys of the array are PDO driver names while the values are either the corresponding schema class names or configurations. Please refer to Yii::createObject() for details on how to specify a configuration.

This property is mainly used by getSchema() when fetching the database schema information. You normally do not need to set this property unless you want to use your own yii\db\Schema class to support DBMS that is not supported by Yii.

public array $schemaMap = ['pgsql' => 'yii\db\pgsql\Schema', 'mysqli' => 'yii\db\mysql\Schema', 'mysql' => 'yii\db\mysql\Schema', 'sqlite' => 'yii\db\sqlite\Schema', 'sqlite2' => 'yii\db\sqlite\Schema', 'sqlsrv' => 'yii\db\mssql\Schema', 'oci' => 'yii\db\oci\Schema', 'mssql' => 'yii\db\mssql\Schema', 'dblib' => 'yii\db\mssql\Schema', 'cubrid' => 'yii\db\cubrid\Schema']
$serverRetryInterval public property

The retry interval in seconds for dead servers listed in $masters and $slaves. This is used together with $serverStatusCache.

public integer $serverRetryInterval = 600
$serverStatusCache public property

The cache object or the ID of the cache application component that is used to store the health status of the DB servers specified in $masters and $slaves. This is used only when read/write splitting is enabled or $masters is not empty. Set boolean `false` to disabled server status caching.

See also:

- openFromPoolSequentially() for details about the failover behavior.
- $serverRetryInterval

public yii\caching\CacheInterface|string|false $serverStatusCache = 'cache'
$serverVersion public property

Server version as a string. This property is read-only.

public string $serverVersion = null
$shuffleMasters public property (available since version 2.0.11)

Whether to shuffle $masters before getting one.

See also $masters.

public boolean $shuffleMasters = true
$slave public property

The currently active slave connection. `null` is returned if there is no slave available and `$fallbackToMaster` is false. This property is read-only.

public yii\db\Connection $slave = null
$slaveConfig public property

The configuration that should be merged with every slave configuration listed in $slaves. For example,

    [
        'username' => 'slave',
        'password' => 'slave',
        'attributes' => [
            // use a smaller connection timeout
            PDO::ATTR_TIMEOUT => 10,
        ],
    ]

public array $slaveConfig = []
$slavePdo public property

The PDO instance for the currently active slave connection. `null` is returned if no slave connection is available and `$fallbackToMaster` is false. This property is read-only.

public PDO $slavePdo = null
$slaves public property

List of slave connection configurations. Each configuration is used to create a slave DB connection. When $enableSlaves is true, one of these configurations will be chosen and used to create a DB connection for performing read queries only.

See also:

- $enableSlaves
- $slaveConfig

public array $slaves = []
$tablePrefix public property

The common prefix or suffix for table names. If a table name is given as `{{%TableName}}`, then the percentage character `%` will be replaced with this property value. For example, `{{%post}}` becomes `{{tbl_post}}`.

public string $tablePrefix = ''
$transaction public property

The currently active transaction. Null if no active transaction. This property is read-only.

public yii\db\Transaction|null $transaction = null
$username public property

The username for establishing DB connection. Defaults to `null` meaning no username to use.

public string $username = null

## Method Details

__clone() public method

Reset the connection after cloning.

public void __clone ( )

__sleep() public method

Close the connection before serializing.

public array __sleep ( )

beginTransaction() public method

Starts a transaction.

public yii\db\Transaction beginTransaction ( $isolationLevel = null )
$isolationLevel | string|null | The isolation level to use for this transaction. See yii\db\Transaction::begin() for details.
return | yii\db\Transaction | The transaction initiated

cache() public method

Uses query cache for the queries performed with the callable.

When query caching is enabled ($enableQueryCache is true and $queryCache refers to a valid cache), queries performed within the callable will be cached and their results will be fetched from cache if available. For example,

    // The customer will be fetched from cache if available.
    // If not, the query will be made against DB and cached for use next time.
    $customer = $db->cache(function (Connection $db) {
        return $db->createCommand('SELECT * FROM customer WHERE id=1')->queryOne();
    });

Note that query cache is only meaningful for queries that return results. For queries performed with yii\db\Command::execute(), query cache will not be used.

See also:

- $enableQueryCache
- $queryCache
- noCache()

public mixed cache ( callable $callable, $duration = null, $dependency = null )
$callable | callable | A PHP callable that contains DB queries which will make use of query cache. The signature of the callable is `function (Connection $db)`.
$duration | integer | The number of seconds that query results can remain valid in the cache. If this is not set, the value of $queryCacheDuration will be used instead. Use 0 to indicate that the cached data will never expire.
$dependency | yii\caching\Dependency | The cache dependency associated with the cached query results.
return | mixed | The return result of the callable
throws | \Exception|\Throwable | if there is any exception during query

close() public method

Closes the currently active DB connection.

It does nothing if the connection is already closed.

public void close ( )

createCommand() public method

Creates a command for execution.

public yii\db\Command createCommand ( $sql = null, $params = [] )
$sql | string | The SQL statement to be executed
$params | array | The parameters to be bound to the SQL statement
return | yii\db\Command | The DB command

createPdoInstance() protected method

Creates the PDO instance.

This method is called by open() to establish a DB connection. The default implementation will create a PHP PDO instance. You may override this method if the default PDO needs to be adapted for certain DBMS.

protected PDO createPdoInstance ( )
return | PDO | The pdo instance

getDriverName() public method

Returns the name of the DB driver. Based on the the current $dsn, in case it was not set explicitly by an end user.

public string getDriverName ( )
return | string | Name of the DB driver

getIsActive() public method

Returns a value indicating whether the DB connection is established.

public boolean getIsActive ( )
return | boolean | Whether the DB connection is established

getLastInsertID() public method

Returns the ID of the last inserted row or sequence value.

See also https://secure.php.net/manual/en/pdo.lastinsertid.php.

public string getLastInsertID ( $sequenceName = '' )
$sequenceName | string | Name of the sequence object (required by some DBMS)
return | string | The row ID of the last row inserted, or the last value retrieved from the sequence object

getMaster() public method (available since version 2.0.11)

Returns the currently active master connection.

If this method is called for the first time, it will try to open a master connection.

public yii\db\Connection getMaster ( )
return | yii\db\Connection | The currently active master connection. `null` is returned if there is no master available.

getMasterPdo() public method

Returns the PDO instance for the currently active master connection.

This method will open the master DB connection and then return $pdo.

public PDO getMasterPdo ( )
return | PDO | The PDO instance for the currently active master connection.

getQueryBuilder() public method

Returns the query builder for the current DB connection.

public yii\db\QueryBuilder getQueryBuilder ( )
return | yii\db\QueryBuilder | The query builder for the current DB connection.

getQueryCacheInfo() public method

Returns the current query cache information.

This method is used internally by yii\db\Command.

public array getQueryCacheInfo ( $duration, $dependency )
$duration | integer | The preferred caching duration. If null, it will be ignored.
$dependency | yii\caching\Dependency | The preferred caching dependency. If null, it will be ignored.
return | array | The current query cache information, or null if query cache is not enabled.

getSchema() public method

Returns the schema information for the database opened by this connection.

public yii\db\Schema getSchema ( )
return | yii\db\Schema | The schema information for the database opened by this connection.
throws | yii\base\NotSupportedException | if there is no support for the current driver type

getServerVersion() public method (available since version 2.0.14)

Returns a server version as a string comparable by \version_compare().

public string getServerVersion ( )
return | string | Server version as a string.

getSlave() public method

Returns the currently active slave connection.

If this method is called for the first time, it will try to open a slave connection when $enableSlaves is true.

public yii\db\Connection getSlave ( $fallbackToMaster = true )
$fallbackToMaster | boolean | Whether to return a master connection in case there is no slave connection available.
return | yii\db\Connection | The currently active slave connection. `null` is returned if there is no slave available and `$fallbackToMaster` is false.

getSlavePdo() public method

Returns the PDO instance for the currently active slave connection.

When $enableSlaves is true, one of the slaves will be used for read queries, and its PDO instance will be returned by this method.

public PDO getSlavePdo ( $fallbackToMaster = true )
$fallbackToMaster | boolean | Whether to return a master PDO in case none of the slave connections is available.
return | PDO | The PDO instance for the currently active slave connection. `null` is returned if no slave connection is available and `$fallbackToMaster` is false.

getTableSchema() public method

Obtains the schema information for the named table.

public yii\db\TableSchema getTableSchema ( $name, $refresh = false )
$name | string | Table name.
$refresh | boolean | Whether to reload the table schema even if it is found in the cache.
return | yii\db\TableSchema | Table schema information. Null if the named table does not exist.

getTransaction() public method

Returns the currently active transaction.

public yii\db\Transaction|null getTransaction ( )
return | yii\db\Transaction|null | The currently active transaction. Null if no active transaction.

initConnection() protected method

Initializes the DB connection.

This method is invoked right after the DB connection is established. The default implementation turns on `PDO::ATTR_EMULATE_PREPARES` if $emulatePrepare is true, and sets the database $charset if it is not empty. It then triggers an EVENT_AFTER_OPEN event.

protected void initConnection ( )

noCache() public method

Disables query cache temporarily.

Queries performed within the callable will not use query cache at all. For example,

    $db->cache(function (Connection $db) {

        // ... queries that use query cache ...

        return $db->noCache(function (Connection $db) {
            // this query will not use query cache
            return $db->createCommand('SELECT * FROM customer WHERE id=1')->queryOne();
        });
    });

See also:

- $enableQueryCache
- $queryCache
- cache()

public mixed noCache ( callable $callable )
$callable | callable | A PHP callable that contains DB queries which should not use query cache. The signature of the callable is `function (Connection $db)`.
return | mixed | The return result of the callable
throws | \Exception|\Throwable | if there is any exception during query

open() public method

Establishes a DB connection.

It does nothing if a DB connection has already been established.

public void open ( )
throws | yii\db\Exception | if connection fails

openFromPool() protected method

Opens the connection to a server in the pool.

This method implements load balancing and failover among the given list of the servers. Connections will be tried in random order. For details about the failover behavior, see openFromPoolSequentially().

See also openFromPoolSequentially().

protected yii\db\Connection openFromPool ( array $pool, array $sharedConfig )
$pool | array | The list of connection configurations in the server pool
$sharedConfig | array | The configuration common to those given in `$pool`.
return | yii\db\Connection | The opened DB connection, or `null` if no server is available
throws | yii\base\InvalidConfigException | if a configuration does not specify "dsn"

openFromPoolSequentially() protected method (available since version 2.0.11)

Opens the connection to a server in the pool.

This method implements failover among the given list of servers. Connections will be tried in sequential order. The first successful connection will return.

If $serverStatusCache is configured, this method will cache information about unreachable servers and does not try to connect to these for the time configured in $serverRetryInterval. This helps to keep the application stable when some servers are unavailable. Avoiding connection attempts to unavailable servers saves time when the connection attempts fail due to timeout.

If none of the servers are available the status cache is ignored and connection attempts are made to all servers (Since version 2.0.35). This is to avoid downtime when all servers are unavailable for a short time. After a successful connection attempt the server is marked as available again.

See also:

- openFromPool()
- $serverStatusCache

protected yii\db\Connection openFromPoolSequentially ( array $pool, array $sharedConfig )
$pool | array | The list of connection configurations in the server pool
$sharedConfig | array | The configuration common to those given in `$pool`.
return | yii\db\Connection | The opened DB connection, or `null` if no server is available
throws | yii\base\InvalidConfigException | if a configuration does not specify "dsn"

quoteColumnName() public method

Quotes a column name for use in a query.

If the column name contains prefix, the prefix will also be properly quoted. If the column name is already quoted or contains special characters including '(', '[[' and '{{', then this method will do nothing.

public string quoteColumnName ( $name )
$name | string | Column name
return | string | The properly quoted column name

quoteSql() public method

Processes a SQL statement by quoting table and column names that are enclosed within double brackets.

Tokens enclosed within double curly brackets are treated as table names, while tokens enclosed within double square brackets are column names. They will be quoted accordingly. Also, the percentage character "%" at the beginning or ending of a table name will be replaced with $tablePrefix.

public string quoteSql ( $sql )
$sql | string | The SQL to be quoted
return | string | The quoted SQL

quoteTableName() public method

Quotes a table name for use in a query.

If the table name contains schema prefix, the prefix will also be properly quoted. If the table name is already quoted or contains special characters including '(', '[[' and '{{', then this method will do nothing.

public string quoteTableName ( $name )
$name | string | Table name
return | string | The properly quoted table name

quoteValue() public method

Quotes a string value for use in a query.

Note that if the parameter is not a string, it will be returned without change.

See also https://secure.php.net/manual/en/pdo.quote.php.

public string quoteValue ( $value )
$value | string | String to be quoted
return | string | The properly quoted string

setDriverName() public method

Changes the current driver name.

public void setDriverName ( $driverName )
$driverName | string | Name of the DB driver

setQueryBuilder() public method (available since version 2.0.14)

Can be used to set yii\db\QueryBuilder configuration via Connection configuration array.

public void setQueryBuilder ( $value )
$value | array | The yii\db\QueryBuilder properties to be configured.

transaction() public method

Executes callback provided in a transaction.

public mixed transaction ( callable $callback, $isolationLevel = null )
$callback | callable | A valid PHP callback that performs the job. Accepts connection instance as parameter.
$isolationLevel | string|null | The isolation level to use for this transaction. See yii\db\Transaction::begin() for details.
return | mixed | Result of callback function
throws | \Exception|\Throwable | if there is any exception during query. In this case the transaction will be rolled back.

useMaster() public method

Executes the provided callback by using the master connection.

This method is provided so that you can temporarily force using the master connection to perform DB operations even if they are read queries. For example,

    $result = $db->useMaster(function ($db) {
        return $db->createCommand('SELECT * FROM user LIMIT 1')->queryOne();
    });

public mixed useMaster ( callable $callback )
$callback | callable | A PHP callable to be executed by this method. Its signature is `function (Connection $db)`. Its return value will be returned by this method.
return | mixed | The return value of the callback
throws | \Exception|\Throwable | if there is any exception thrown from the callback

## Event Details

EVENT_AFTER_OPEN event of type \yii\db\yii\base\Event

An event that is triggered after a DB connection is established

EVENT_BEGIN_TRANSACTION event of type \yii\db\yii\base\Event

An event that is triggered right before a top-level transaction is started

EVENT_COMMIT_TRANSACTION event of type \yii\db\yii\base\Event

An event that is triggered right after a top-level transaction is committed

EVENT_ROLLBACK_TRANSACTION event of type \yii\db\yii\base\Event

An event that is triggered right after a top-level transaction is rolled back