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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', ], ], ~~~ Mostra 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

Property Details