Class yii\db\Connection

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 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;'.

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.

参见 createCommand().

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.

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.

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

参见 $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 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.

参见 $enableProfiling.

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.

参见 $enableLogging.

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.

参见：

• $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.

参见：

• $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 currently active master connection. null is returned if there is no master available.

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.

参见：

• $masterConfig
• $shuffleMasters

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.

参见 $pdoClass.

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

参见 $pdo.

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.

参见 $enableQueryCache.

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.

参见：

• $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.

参见 $enableSchemaCache.

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

参见 $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.

参见 $enableSchemaCache.

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.

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. Set boolean false to disabled server status caching.

Server version as a string.

Whether to shuffle $masters before getting one.

参见 $masters.

The currently active slave connection. null is returned if there is no 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.

参见：

• $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.