Execute a database command that reads

# MongoDB\Driver\Manager::executeReadCommand

(mongodb >=1.4.0)

MongoDB\Driver\Manager::executeReadCommand — Execute a database command that reads

### Descrierea

final public MongoDB\Driver\Manager::executeReadCommand ( string `$db` , MongoDB\Driver\Command `$command` [, array `$options` = array() ] ) : MongoDB\Driver\Cursor

Selects a server according to the "readPreference" option and executes the command on that server. By default, the read preference from the MongoDB Connection URI will be used.

This method will apply logic that is specific to commands that read (e.g. » count) and take the MongoDB server version into account. The "readConcern" option will default to the corresponding value from the MongoDB Connection URI.

### Parametri

`db` (string)

  Denumirea bazei de date asupra căreia va fi executată comanda.

`command` (MongoDB\Driver\Command)

  MongoDB\Driver\Command spre a fi executată.

`options`

  options
  Option | Type | Description
  --- | --- | ---
  readConcern | MongoDB\Driver\ReadConcern | A read concern to apply to the operation. This option is available in MongoDB 3.2+ and will result in an exception at execution time if specified for an older server version.
  readPreference | MongoDB\Driver\ReadPreference | A read preference to use for selecting a server for the operation.
  session | MongoDB\Driver\Session | A session to associate with the operation.

  Avertizare

  If you are using a "session" which has a transaction in progress, you cannot specify a "readConcern" or "writeConcern" option. This will result in an MongoDB\Driver\Exception\InvalidArgumentException being thrown. Instead, you should set these two options when you create the transaction with MongoDB\Driver\Session::startTransaction().

### Valorile întoarse

Întoarce MongoDB\Driver\Cursor în caz de succes.

### Erori/Excepții

- Throws MongoDB\Driver\Exception\InvalidArgumentException if the "session" option is used with an associated transaction in combination with a "readConcern" or "writeConcern" option.
- Emite MongoDB\Driver\Exception\InvalidArgumentException în cazul erorilor la interpretarea argumentelor.
- Emite MongoDB\Driver\Exception\ConnectionException dacă conexiunea către server eșuează (din alte motive decât autentificarea).
- Emite MongoDB\Driver\Exception\AuthenticationException dacă este necesară autentificare și aceasta eșuează.
- Throws MongoDB\Driver\Exception\RuntimeException on other errors (e.g. invalid command).

### A se vedea și

- MongoDB\Driver\Command
- MongoDB\Driver\Cursor
- MongoDB\Driver\Manager::executeCommand() - Execute a database command
- MongoDB\Driver\Manager::executeReadWriteCommand() - Execute a database command that reads and writes
- MongoDB\Driver\Manager::executeWriteCommand() - Execute a database command that writes
- MongoDB\Driver\Server::executeReadCommand() - Execute a database command that reads on this server