Connection

API reference › yii › db › Connection

class	`yii\db\Connection`
Extends	`yii\base\Component` » `yii\base\BaseObject`
Implements	`yii\base\Configurable`
Since	2.0
Source	`framework/db/Connection.php`

Connection represents a connection to a database via PDO.

Connection works together with Command, DataReader and 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 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' => 'utf8mb4',
    ],
],

Properties

Property	Type	Description	Defined by
`$attributes`	`array`	PDO attributes (name => value) that should be set when calling `open()` to establish a DB connection. Default: `null`.	`Connection`
`$behaviors` read-only	`array<yii\base\Behavior<static>>`	List of behaviors attached to this component.	`yii\base\Component`
`$charset`	`string\|null`	The charset used for database connection. Default: `null`.	`Connection`
`$commandMap`	`array`	Mapping between PDO driver names and `Command` classes. Default: `['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\mssql\Command', 'oci' => 'yii\db\oci\Command', 'mssql' => 'yii\db\mssql\Command', 'dblib' => 'yii\db\mssql\Command']`. Available since 2.0.14.	`Connection`
`$driverName`	`string`	Name of the DB driver.	`Connection`
`$dsn`	`string`	The Data Source Name, or DSN, contains the information required to connect to the database. Default: `null`.	`Connection`
`$effectiveCharset` read-only	`string\|null`	The effective connection charset, or `null` when the connection relies on the database server defaults.	`Connection`
`$emulatePrepare`	`bool\|null`	Whether to turn on prepare emulation. Default: `null`.	`Connection`
`$enableLogging`	`bool`	Whether to enable logging of database queries. Default: `true`. Available since 2.0.12.	`Connection`
`$enableProfiling`	`bool`	Whether to enable profiling of opening database connection and database queries. Default: `true`. Available since 2.0.12.	`Connection`
`$enableQueryCache`	`bool`	Whether to enable query caching. Default: `true`.	`Connection`
`$enableSavepoint`	`bool`	Whether to enable savepoint. Default: `true`.	`Connection`
`$enableSchemaCache`	`bool`	Whether to enable schema caching. Default: `false`.	`Connection`
`$enableSlaves`	`bool`	Whether to enable read/write splitting by using `$slaves` to read data. Default: `true`.	`Connection`
`$isActive` read-only	`bool`	Whether the DB connection is established.	`Connection`
`$isSybase`	`bool`	If the database connected via pdo_dblib is SyBase. Default: `false`. Available since 2.0.38.	`Connection`
`$lastInsertID` read-only	`string`	The row ID of the last row inserted, or the last value retrieved from the sequence object.	`Connection`
`$master` read-only	`Connection\|null`	The currently active master connection. `null` is returned if there is no master available.	`Connection`
`$masterConfig`	`array`	The configuration that should be merged with every master configuration listed in `$masters`. Default: `[]`.	`Connection`
`$masterPdo` read-only	`PDO`	The PDO instance for the currently active master connection.	`Connection`
`$masters`	`array`	List of master connection configurations. Default: `[]`.	`Connection`
`$password`	`string\|null`	The password for establishing DB connection. Default: `null`.	`Connection`
`$pdo`	`PDO\|null`	The PHP PDO instance associated with this DB connection. Default: `null`.	`Connection`
`$pdoClass`	`string\|null`	Custom PDO wrapper class. Default: `null`.	`Connection`
`$queryBuilder`	`array`	The `QueryBuilder` properties to be configured.	`Connection`
`$queryCache`	`yii\caching\CacheInterface\|string`	The cache object or the ID of the cache application component that is used for query caching. Default: `'cache'`.	`Connection`
`$queryCacheDuration`	`int`	The default number of seconds that query results can remain valid in cache. Default: `3600`.	`Connection`
`$schema` read-only	`yii\db\TSchema`	The schema information for the database opened by this connection.	`Connection`
`$schemaCache`	`yii\caching\CacheInterface\|string`	The cache object or the ID of the cache application component that is used to cache the table metadata. Default: `'cache'`.	`Connection`
`$schemaCacheDuration`	`int`	Number of seconds that table metadata can remain valid in cache. Default: `3600`.	`Connection`
`$schemaCacheExclude`	`array`	List of tables whose metadata should NOT be cached. Default: `[]`.	`Connection`
`$schemaMap`	`array`	Mapping between PDO driver names and `Schema` classes. Default: `['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']`.	`Connection`
`$serverRetryInterval`	`int`	The retry interval in seconds for dead servers listed in `$masters` and `$slaves`. Default: `600`.	`Connection`
`$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`. Default: `'cache'`.	`Connection`
`$serverVersion` read-only	`string`	Server version as a string.	`Connection`
`$shuffleMasters`	`bool`	Whether to shuffle `$masters` before getting one. Default: `true`. Available since 2.0.11.	`Connection`
`$slave` read-only	`Connection\|null`	The currently active slave connection. `null` is returned if there is no slave available and `$fallbackToMaster` is false.	`Connection`
`$slaveConfig`	`array`	The configuration that should be merged with every slave configuration listed in `$slaves`. Default: `[]`.	`Connection`
`$slavePdo` read-only	`PDO\|null`	The PDO instance for the currently active slave connection. `null` is returned if no slave connection is available and `$fallbackToMaster` is false.	`Connection`
`$slaves`	`array`	List of slave connection configurations. Default: `[]`.	`Connection`
`$tablePrefix`	`string`	The common prefix or suffix for table names. Default: `''`.	`Connection`
`$transaction` read-only	`Transaction\|null`	The currently active transaction.	`Connection`
`$transactionMap`	`array<string, class-string<Transaction>\|array<string, mixed>>`	Mapping between PDO driver names and `Transaction` classes or configurations. Default: `['pgsql' => \yii\db\pgsql\Transaction::class, 'mysqli' => \yii\db\Transaction::class, 'mysql' => \yii\db\Transaction::class, 'sqlite' => \yii\db\Transaction::class, 'sqlite2' => \yii\db\Transaction::class, 'sqlsrv' => \yii\db\Transaction::class, 'oci' => \yii\db\Transaction::class, 'mssql' => \yii\db\Transaction::class, 'dblib' => \yii\db\Transaction::class]`. Available since 22.0.	`Connection`
`$username`	`string\|null`	The username for establishing DB connection. Default: `null`.	`Connection`

Methods

Method	Description	Defined by
`__construct()`	Constructor.	`yii\base\BaseObject`
`__call()`	Calls the named method which is not a class method.	`yii\base\Component`
`__clone()`	Reset the connection after cloning.	`Connection`
`__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.	`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.	`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.	`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()` static	Returns the fully qualified name of this class.	`yii\base\BaseObject`
`close()`	Closes the currently active DB connection.	`Connection`
`createCommand()`	Creates a command for execution.	`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.	`Connection`
`getEffectiveCharset()`	Returns the charset the connection effectively uses.	`Connection`
`getIsActive()`	Returns a value indicating whether the DB connection is established.	`Connection`
`getLastInsertID()`	Returns the ID of the last inserted row or sequence value.	`Connection`
`getMaster()`	Returns the currently active master connection.	`Connection`
`getMasterPdo()`	Returns the PDO instance for the currently active master connection.	`Connection`
`getQueryBuilder()`	Returns the query builder for the current DB connection.	`Connection`
`getSchema()`	Returns the schema information for the database opened by this connection.	`Connection`
`getServerVersion()`	Returns a server version as a string comparable by `version_compare()`.	`Connection`
`getSlave()`	Returns the currently active slave connection.	`Connection`
`getSlavePdo()`	Returns the PDO instance for the currently active slave connection.	`Connection`
`getTableSchema()`	Obtains the schema information for the named table.	`Connection`
`getTransaction()`	Returns the currently active transaction.	`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.	`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.	`Connection`
`quoteColumnName()`	Quotes a column name for use in a query.	`Connection`
`quoteSql()`	Processes a SQL statement by quoting table and column names that are enclosed within double brackets.	`Connection`
`quoteTableName()`	Quotes a table name for use in a query.	`Connection`
`quoteValue()`	Quotes a string value for use in a query.	`Connection`
`setDriverName()`	Changes the current driver name.	`Connection`
`setQueryBuilder()`	Can be used to set `QueryBuilder` configuration via Connection configuration array.	`Connection`
`transaction()`	Executes callback provided in a transaction.	`Connection`
`trigger()`	Triggers an event.	`yii\base\Component`
`useMaster()`	Executes the provided callback by using the master connection.	`Connection`
`createPdoInstance()` protected	Creates the PDO instance.	`Connection`
`initConnection()` protected	Initializes the DB connection.	`Connection`
`openFromPool()` protected	Opens the connection to a server in the pool.	`Connection`
`openFromPoolSequentially()` protected	Opens the connection to a server in the pool.	`Connection`

Events

Event	Type	Description	Defined by
`EVENT_AFTER_OPEN`	`yii\base\Event`	An event that is triggered after a DB connection is established Event name: `'afterOpen'`.	`Connection`
`EVENT_BEGIN_TRANSACTION`	`yii\base\Event`	An event that is triggered right before a top-level transaction is started Event name: `'beginTransaction'`.	`Connection`
`EVENT_COMMIT_TRANSACTION`	`yii\base\Event`	An event that is triggered right after a top-level transaction is committed Event name: `'commitTransaction'`.	`Connection`
`EVENT_ROLLBACK_TRANSACTION`	`yii\base\Event`	An event that is triggered right after a top-level transaction is rolled back Event name: `'rollbackTransaction'`.	`Connection`

Property details

$attributes

public array $attributes = null

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.

$charset

public string|null $charset = null

The charset used for database connection.

The property is only used for MySQL and PostgreSQL databases. Defaults to null. MySQL and MariaDB connections use utf8mb4 when neither this property nor the $dsn specifies a charset. PostgreSQL connections use the default charset 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;'.

$commandMap

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\mssql\Command', 'oci' => 'yii\db\oci\Command', 'mssql' => 'yii\db\mssql\Command', 'dblib' => 'yii\db\mssql\Command']

Mapping between PDO driver names and 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 Command objects. You normally do not need to set this property unless you want to use your own Command class or support DBMS that is not supported by Yii.

Since

2.0.14

$dsn

public string $dsn = null

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.

$emulatePrepare

public bool|null $emulatePrepare = null

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.

$enableLogging

public bool $enableLogging = true

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.

Since

2.0.12

$enableProfiling

public bool $enableProfiling = true

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.

Since

2.0.12

$enableQueryCache

public bool $enableQueryCache = true

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.

$enableSavepoint

public bool $enableSavepoint = true

Whether to enable savepoint.

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

$enableSchemaCache

public bool $enableSchemaCache = false

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.

$enableSlaves

public bool $enableSlaves = true

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.

$masterConfig

public array $masterConfig = []

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,
    ],
]

$masters

public array $masters = []

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.

$password

public string|null $password = null

The password for establishing DB connection.

Defaults to null meaning no password to use.

$pdo

public PDO|null $pdo = null

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.

$pdoClass

public string|null $pdoClass = null

Custom PDO wrapper class.

If not set, it will use PDO or PDO when MSSQL is used.

$queryCacheDuration

public int $queryCacheDuration = 3600

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.

$schemaCacheDuration

public int $schemaCacheDuration = 3600

Number of seconds that table metadata can remain valid in cache.

Use 0 to indicate that the cached data will never expire.

$schemaCacheExclude

public array $schemaCacheExclude = []

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.

$schemaMap

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']

Mapping between PDO driver names and 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 Schema class to support DBMS that is not supported by Yii.

$serverRetryInterval

public int $serverRetryInterval = 600

The retry interval in seconds for dead servers listed in $masters and $slaves.

This is used together with $serverStatusCache.

$serverStatusCache

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

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.

$slaveConfig

public array $slaveConfig = []

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,
    ],
]

$slaves

public array $slaves = []

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.

$tablePrefix

public string $tablePrefix = ''

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}}.

$transaction

public yii\db\Transaction|null $transaction

The currently active transaction.

Null if no active transaction.

Access

Read-only (virtual property).

$transactionMap

public array<string, class-string<yii\db\Transaction>|array<string, mixed>> $transactionMap = ['pgsql' => \yii\db\pgsql\Transaction::class, 'mysqli' => \yii\db\Transaction::class, 'mysql' => \yii\db\Transaction::class, 'sqlite' => \yii\db\Transaction::class, 'sqlite2' => \yii\db\Transaction::class, 'sqlsrv' => \yii\db\Transaction::class, 'oci' => \yii\db\Transaction::class, 'mssql' => \yii\db\Transaction::class, 'dblib' => \yii\db\Transaction::class]

Mapping between PDO driver names and Transaction classes or configurations.

The keys of the array are PDO driver names while the values are either the corresponding transaction class names or configurations. Please refer to Yii::createObject() for details on how to specify a configuration.

This property is mainly used by beginTransaction() to start new database Transaction objects.

You normally do not need to set this property unless you want to use your own Transaction class or support DBMS that is not supported by Yii.

Since

22.0

$username

public string|null $username = null

The username for establishing DB connection.

Defaults to null meaning no username to use.

Method details

__clone()

public function __clone(): mixed

Reset the connection after cloning.

Returns

mixed

__sleep()

public function __sleep(): array

Close the connection before serializing.

Returns

array

beginTransaction()

public function beginTransaction(string|null $isolationLevel = null): yii\db\Transaction

Starts a transaction.

Parameters

Parameter	Type	Description
`$isolationLevel`	`string\|null`	The isolation level to use for this transaction. See `Transaction::begin()` for details.

Returns

Transaction: The transaction initiated

cache()

public function cache(callable $callable, int|null $duration = null, yii\caching\Dependency|null $dependency = null): mixed

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 Command::execute(), query cache will not be used.

Parameters

Parameter	Type	Description
`$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`	`int\|null`	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\|null`	The cache dependency associated with the cached query results.

Returns

mixed: The return result of the callable

Throws

Throwable: if there is any exception during query

See also

close()

public function close(): mixed

Closes the currently active DB connection.

It does nothing if the connection is already closed.

Returns

mixed

createCommand()

public function createCommand(string|null $sql = null, array $params = []): yii\db\Command

Creates a command for execution.

Parameters

Parameter	Type	Description
`$sql`	`string\|null`	The SQL statement to be executed
`$params`	`array`	The parameters to be bound to the SQL statement

Returns

Command: The DB command

getDriverName()

public function getDriverName(): string|null

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

Returns

string|null: Name of the DB driver

getEffectiveCharset()

public function getEffectiveCharset(): string|null

Returns the charset the connection effectively uses.

Resolution order: $charset when set, then a charset element in the $dsn, then utf8mb4 for MySQL and MariaDB. The value derives from the configuration only, so it is available before the connection is opened.

Returns

string|null: The effective connection charset, or null when the connection relies on the database server defaults.

Since

22.0

getIsActive()

public function getIsActive(): bool

Returns a value indicating whether the DB connection is established.

Returns

bool: Whether the DB connection is established

getLastInsertID()

public function getLastInsertID(string $sequenceName = ''): string

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

Parameters

Parameter	Type	Description
`$sequenceName`	`string`	Name of the sequence object (required by some DBMS)

Returns

string: The row ID of the last row inserted, or the last value retrieved from the sequence object

See also

https://www.php.net/manual/en/pdo.lastinsertid.php

getMaster()

public function getMaster(): yii\db\Connection|null

Returns the currently active master connection.

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

Returns

Connection|null: The currently active master connection. null is returned if there is no master available.

Since

2.0.11

getMasterPdo()

public function getMasterPdo(): PDO

Returns the PDO instance for the currently active master connection.

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

Returns

PDO: The PDO instance for the currently active master connection.

getQueryBuilder()

public function getQueryBuilder(): yii\db\TQueryBuilder

Returns the query builder for the current DB connection.

Returns

yii\db\TQueryBuilder: The query builder for the current DB connection.

getSchema()

public function getSchema(): yii\db\TSchema

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

Returns

yii\db\TSchema: 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 function getServerVersion(): string

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

Returns

string: Server version as a string.

Since

2.0.14

getSlave()

public function getSlave(bool $fallbackToMaster = true): yii\db\Connection|null

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.

Parameters

Parameter	Type	Description
`$fallbackToMaster`	`bool`	Whether to return a master connection in case there is no slave connection available.

Returns

Connection|null: The currently active slave connection. null is returned if there is no slave available and $fallbackToMaster is false.

getSlavePdo()

public function getSlavePdo(bool $fallbackToMaster = true): PDO|null

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.

Parameters

Parameter	Type	Description
`$fallbackToMaster`	`bool`	Whether to return a master PDO in case none of the slave connections is available.

Returns

PDO|null: The PDO instance for the currently active slave connection. null is returned if no slave connection is available and $fallbackToMaster is false.

getTableSchema()

public function getTableSchema(string $name, bool $refresh = false): yii\db\TableSchema|null

Obtains the schema information for the named table.

Parameters

Parameter	Type	Description
`$name`	`string`	Table name.
`$refresh`	`bool`	Whether to reload the table schema even if it is found in the cache.

Returns

TableSchema|null: Table schema information. Null if the named table does not exist.

getTransaction()

public function getTransaction(): yii\db\Transaction|null

Returns the currently active transaction.

Returns

Transaction|null: The currently active transaction. Null if no active transaction.

noCache()

public function noCache(callable $callable): mixed

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();
    });
});

Parameters

Parameter	Type	Description
`$callable`	`callable`	A PHP callable that contains DB queries which should not use query cache. The signature of the callable is `function (Connection $db)`.

Returns

mixed: The return result of the callable

Throws

Throwable: if there is any exception during query

See also

open()

public function open(): mixed

Establishes a DB connection.

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

Returns

mixed

Throws

Exception: if connection fails

quoteColumnName()

public function quoteColumnName(string $name): string

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.

Parameters

Parameter	Type	Description
`$name`	`string`	Column name

Returns

string: The properly quoted column name

quoteSql()

public function quoteSql(string $sql): string

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.

Parameters

Parameter	Type	Description
`$sql`	`string`	The SQL to be quoted

Returns

string: The quoted SQL

quoteTableName()

public function quoteTableName(string $name): string

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.

Parameters

Parameter	Type	Description
`$name`	`string`	Table name

Returns

string: The properly quoted table name

quoteValue()

public function quoteValue(string $value): string

Quotes a string value for use in a query.

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

Parameters

Parameter	Type	Description
`$value`	`string`	String to be quoted

Returns

string: The properly quoted string

See also

https://www.php.net/manual/en/pdo.quote.php

setDriverName()

public function setDriverName(string $driverName): mixed

Changes the current driver name.

Parameters

Parameter	Type	Description
`$driverName`	`string`	Name of the DB driver

Returns

mixed

setQueryBuilder()

public function setQueryBuilder(array $value): mixed

Can be used to set QueryBuilder configuration via Connection configuration array.

Parameters

Parameter	Type	Description
`$value`	`array`	The `QueryBuilder` properties to be configured.

Returns

mixed

Since

2.0.14

transaction()

public function transaction(callable $callback, string|null $isolationLevel = null): mixed

Executes callback provided in a transaction.

Parameters

Parameter	Type	Description
`$callback`	`callable`	A valid PHP callback that performs the job. Accepts connection instance as parameter.
`$isolationLevel`	`string\|null`	The isolation level to use for this transaction. See `Transaction::begin()` for details.

Returns

mixed: Result of callback function

Throws

Throwable: if there is any exception during query. In this case the transaction will be rolled back.

useMaster()

public function useMaster(callable $callback): mixed

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();
});

Parameters

Parameter	Type	Description
`$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.

Returns

mixed: The return value of the callback

Throws

Throwable: if there is any exception thrown from the callback

createPdoInstance()

protected function createPdoInstance(): PDO

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.

Returns

PDO: The pdo instance

initConnection()

protected function initConnection(): mixed

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. MySQL and MariaDB connections fall back to utf8mb4 when neither $charset nor the $dsn specifies a charset. For PostgreSQL, an explicitly configured Schema::$defaultSchema is applied as the session search_path. It then triggers an EVENT_AFTER_OPEN event.

Returns

mixed

openFromPool()

protected function openFromPool(array $pool, array $sharedConfig): yii\db\Connection|null

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().

Parameters

Parameter	Type	Description
`$pool`	`array`	The list of connection configurations in the server pool
`$sharedConfig`	`array`	The configuration common to those given in `$pool`.

Returns

Connection|null: The opened DB connection, or null if no server is available

Throws

yii\base\InvalidConfigException: if a configuration does not specify “dsn”

See also

openFromPoolSequentially()

openFromPoolSequentially()

protected function openFromPoolSequentially(array $pool, array $sharedConfig): yii\db\Connection|null

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.

Parameters

Parameter	Type	Description
`$pool`	`array`	The list of connection configurations in the server pool
`$sharedConfig`	`array`	The configuration common to those given in `$pool`.

Returns

Connection|null: The opened DB connection, or null if no server is available

Throws

yii\base\InvalidConfigException: if a configuration does not specify “dsn”

Since

2.0.11

See also