PHP Class yii\db\Connection

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]](http://www.php.net/manual/en/ref.pdo.php). 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 Connection::open to be true. 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' => 'utf8', ], ], ~~~

Since: 2.0

Author: Qiang Xue ([email protected])

Inheritance: extends yii\base\Component

Show file Open project: yiisoft/yii2 Class Usage Examples

Public Properties

Property	Type	Description
$attributes		PDO attributes (name => value) that should be set when calling Connection::open to establish a DB connection. Please refer to the PHP manual for details about available attributes.
$charset		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;'.
$commandClass		the class used to create new database Command objects. If you want to extend the Command class, you may configure this property to use your extended version of the class.
$dsn		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		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.
$enableQueryCache		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 Connection::cache will be cached.
$enableSavepoint		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		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		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		the configuration that should be merged with every master configuration listed in [[masters]]. For example, php [ 'username' => 'master', 'password' => 'master', 'attributes' => [ use a smaller connection timeout PDO::ATTR_TIMEOUT => 10, ], ]
$masters		list of master connection configurations. Each configuration is used to create a master DB connection. When Connection::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		the password for establishing DB connection. Defaults to null meaning no password to use.
$pdo		the PHP PDO instance associated with this DB connection. This property is mainly managed by Connection::open and Connection::close methods. When a DB connection is active, this property will represent a PDO instance; otherwise, it will be null.
$pdoClass		Custom PDO wrapper class. If not set, it will use [[PDO]] or PDO when MSSQL is used.
$queryCache		the cache object or the ID of the cache application component that is used for query caching.
$queryCacheDuration		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 Connection::cache is called without a cache duration.
$schemaCache		the cache object or the ID of the cache application component that is used to cache the table metadata.
$schemaCacheDuration		number of seconds that table metadata can remain valid in cache. Use 0 to indicate that the cached data will never expire.
$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		mapping between PDO driver names and Schema classes. The keys of the array are PDO driver names while the values the corresponding schema class name or configuration. Please refer to [[Yii::createObject()]] for details on how to specify a configuration. This property is mainly used by Connection::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		the retry interval in seconds for dead servers listed in [[masters]] and [[slaves]]. This is used together with [[serverStatusCache]].
$serverStatusCache		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.
$slaveConfig		the configuration that should be merged with every slave configuration listed in [[slaves]]. For example, php [ 'username' => 'slave', 'password' => 'slave', 'attributes' => [ use a smaller connection timeout PDO::ATTR_TIMEOUT => 10, ], ]
$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		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}}.
$username		the username for establishing DB connection. Defaults to null meaning no username to use.

Public Methods

Method	Description
__sleep ( ) : array	Close the connection before serializing.
beginTransaction ( string \| null $isolationLevel = null ) : Transaction	Starts a transaction.
cache ( callable $callable, integer $duration = null, yii\caching\Dependency $dependency = null ) : mixed	Uses query cache for the queries performed with the callable.
close ( )	Closes the currently active DB connection.
createCommand ( string $sql = null, array $params = [] ) : Command	Creates a command for execution.
getDriverName ( ) : string	Returns the name of the DB driver. Based on the the current [[dsn]], in case it was not set explicitly by an end user.
getIsActive ( ) : boolean	Returns a value indicating whether the DB connection is established.
getLastInsertID ( string $sequenceName = '' ) : string	Returns the ID of the last inserted row or sequence value.
getMasterPdo ( ) : PDO	Returns the PDO instance for the currently active master connection.
getQueryBuilder ( ) : QueryBuilder	Returns the query builder for the current DB connection.
getQueryCacheInfo ( integer $duration, yii\caching\Dependency $dependency ) : array	Returns the current query cache information.
getSchema ( ) : Schema	Returns the schema information for the database opened by this connection.
getSlave ( boolean $fallbackToMaster = true ) : Connection	Returns the currently active slave connection.
getSlavePdo ( boolean $fallbackToMaster = true ) : PDO	Returns the PDO instance for the currently active slave connection.
getTableSchema ( string $name, boolean $refresh = false ) : yii\db\TableSchema	Obtains the schema information for the named table.
getTransaction ( ) : Transaction	Returns the currently active transaction.
noCache ( callable $callable ) : mixed	Disables query cache temporarily.
open ( )	Establishes a DB connection.
quoteColumnName ( string $name ) : string	Quotes a column name for use in a query.
quoteSql ( string $sql ) : string	Processes a SQL statement by quoting table and column names that are enclosed within double brackets.
quoteTableName ( string $name ) : string	Quotes a table name for use in a query.
quoteValue ( string $value ) : string	Quotes a string value for use in a query.
setDriverName ( string $driverName )	Changes the current driver name.
transaction ( callable $callback, string \| null $isolationLevel = null ) : mixed	Executes callback provided in a transaction.
useMaster ( callable $callback ) : mixed	Executes the provided callback by using the master connection.

Protected Methods

Method	Description
createPdoInstance ( ) : PDO	Creates the PDO instance.
initConnection ( )	Initializes the DB connection.
openFromPool ( array $pool, array $sharedConfig ) : Connection	Opens the connection to a server in the pool.

Method Details

__sleep() public method

Close the connection before serializing.

public __sleep ( ) : array
return	array

beginTransaction() public method

Starts a transaction.

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

cache() public method

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, php 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.

See also: enableQueryCache

close() public method

It does nothing if the connection is already closed.

public close ( )

createCommand() public method

Creates a command for execution.

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

createPdoInstance() protected method

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 createPdoInstance ( ) : PDO
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 getDriverName ( ) : string
return	string	name of the DB driver

getIsActive() public method

Returns a value indicating whether the DB connection is established.

public getIsActive ( ) : boolean
return	boolean	whether the DB connection is established

getLastInsertID() public method

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

See also: http://www.php.net/manual/en/function.PDO-lastInsertId.php

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

getMasterPdo() public method

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

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

getQueryBuilder() public method

Returns the query builder for the current DB connection.

public getQueryBuilder ( ) : QueryBuilder
return	QueryBuilder	the query builder for the current DB connection.

getQueryCacheInfo() public method

This method is used internally by Command.

public getQueryCacheInfo ( integer $duration, yii\caching\Dependency $dependency ) : array
$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 getSchema ( ) : Schema
return	Schema	the schema information for the database opened by this connection.

getSlave() public method

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

public getSlave ( boolean $fallbackToMaster = true ) : Connection
$fallbackToMaster	boolean	whether to return a master connection in case there is no slave connection available.
return	Connection	the currently active slave connection. Null is returned if there is slave available and `$fallbackToMaster` is false.

getSlavePdo() public method

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

getTableSchema() public method

Obtains the schema information for the named table.

public getTableSchema ( string $name, boolean $refresh = false ) : yii\db\TableSchema
$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 getTransaction ( ) : Transaction
return	Transaction	the currently active transaction. Null if no active transaction.

initConnection() protected method

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 initConnection ( )

noCache() public method

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

open() public method

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

public open ( )

openFromPool() protected method

This method implements the load balancing among the given list of the servers.

protected openFromPool ( array $pool, array $sharedConfig ) : Connection
$pool	array	the list of connection configurations in the server pool
$sharedConfig	array	the configuration common to those given in `$pool`.
return	Connection	the opened DB connection, or null if no server is available

quoteColumnName() public method

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 quoteColumnName ( string $name ) : string
$name	string	column name
return	string	the properly quoted column name

quoteSql() public method

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 quoteSql ( string $sql ) : string
$sql	string	the SQL to be quoted
return	string	the quoted SQL

quoteTableName() public method

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 quoteTableName ( string $name ) : string
$name	string	table name
return	string	the properly quoted table name

quoteValue() public method

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

See also: http://www.php.net/manual/en/function.PDO-quote.php

public quoteValue ( string $value ) : string
$value	string	string to be quoted
return	string	the properly quoted string

setDriverName() public method

Changes the current driver name.

public setDriverName ( string $driverName )
$driverName	string	name of the DB driver

transaction() public method

Executes callback provided in a transaction.

public transaction ( callable $callback, string \| null $isolationLevel = null ) : mixed
$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.
return	mixed	result of callback function

useMaster() public method

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

public useMaster ( callable $callback ) : mixed
$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

Property Details

$attributes public property

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

public $attributes

$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 $charset

$commandClass public property

the class used to create new database Command objects. If you want to extend the Command class, you may configure this property to use your extended version of the class.

$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.

$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 $emulatePrepare

$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 Connection::cache will be cached.

$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 $enableSavepoint

$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.

$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 $enableSlaves

$masterConfig public property

the configuration that should be merged with every master configuration listed in [[masters]]. For example, php [ 'username' => 'master', 'password' => 'master', 'attributes' => [ use a smaller connection timeout PDO::ATTR_TIMEOUT => 10, ], ]

public $masterConfig

$masters public property

list of master connection configurations. Each configuration is used to create a master DB connection. When Connection::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 property

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

public $password

$pdo public property

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

$pdoClass public property

Custom PDO wrapper class. If not set, it will use [[PDO]] or PDO when MSSQL is used.

$queryCache public property

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

See also: enableQueryCache

public $queryCache

$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 Connection::cache is called without a cache duration.

See also: enableQueryCache

$schemaCache public property

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

$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.

$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.

$schemaMap public property

mapping between PDO driver names and Schema classes. The keys of the array are PDO driver names while the values the corresponding schema class name or configuration. Please refer to [[Yii::createObject()]] for details on how to specify a configuration. This property is mainly used by Connection::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.

public $schemaMap

$serverRetryInterval public property

the retry interval in seconds for dead servers listed in [[masters]] and [[slaves]]. This is used together with [[serverStatusCache]].

public $serverRetryInterval

$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.

public $serverStatusCache

$slaveConfig public property

the configuration that should be merged with every slave configuration listed in [[slaves]]. For example, php [ 'username' => 'slave', 'password' => 'slave', 'attributes' => [ use a smaller connection timeout PDO::ATTR_TIMEOUT => 10, ], ]

public $slaveConfig

$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.

$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 $tablePrefix

$username public property

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

public $username

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

public noCache ( callable $callable ) : mixed
$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