Class yii\db\Connection

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

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

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

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

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

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

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

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.

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 specified by the database.

Note that if you're using GBK or BIG5 then it's highly recommended to specify charset via DSN like 'mysql:dbname=mydatabase;host=127.0.0.1;charset=GBK;'.

Name of the DB driver

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.

See also $charset.

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.

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()

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

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

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.

Whether the DB connection is established

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

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,
    ],
]

The PDO instance for the currently active master connection.

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.

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

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.

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

The query builder for the current DB connection.

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

See also $enableQueryCache.

The default number of seconds that query results can remain valid in cache. Use 0 to indicate that the cached data will never expire. 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()

The schema information for the database opened by this connection.

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

See also $enableSchemaCache.

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.

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.

Mapping between PDO driver names and yii\db\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 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.

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

The currently active slave connection. Null is returned if there is slave available and $fallbackToMaster is false.

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,
    ],
]

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

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

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}}.

The currently active transaction. Null if no active transaction.

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

// 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();
});

$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();
    });
});

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