# MongoDB\Driver\Server::executeCommand

(mongodb >=1.0.0)

MongoDB\Driver\Server::executeCommand — Execute a database command on this server

### Description

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

Executes the command on this server.

This method applies no special logic to the command. Although this method accepts `"readConcern"` and `"writeConcern"` options, which will be incorporated into the command document, those options will not default to corresponding values from the MongoDB Connection URI nor will the MongoDB server version be taken into account. Users are therefore encouraged to use specific read and/or write command methods if possible.

> Note: The `"readPreference"` option does not control the server to which the driver issues the operation; it will always be executed on this server object. Instead, it may be used when issuing the operation to a secondary (from a replica set connection, not standalone) or mongos node to ensure that the driver sets the wire protocol accordingly or adds the read preference to the operation, respectively.

### Parameters

`db` (string)

  The name of the database on which to execute the command.

`command` (MongoDB\Driver\Command)

  The command to execute.

`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.
  writeConcern | MongoDB\Driver\WriteConcern | A write concern to apply to the operation.

  Warning

  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().

### Return Values

Returns MongoDB\Driver\Cursor on success.

### Errors/Exceptions

- Throws MongoDB\Driver\Exception\InvalidArgumentException if the `"session"` option is used with an associated transaction in combination with a `"readConcern"` or `"writeConcern"` option.
- Throws MongoDB\Driver\Exception\InvalidArgumentException if the `"session"` option is used in combination with an unacknowledged write concern.
- Throws MongoDB\Driver\Exception\InvalidArgumentException on argument parsing errors.
- Throws MongoDB\Driver\Exception\ConnectionException if connection to the server fails (for reasons other than authentication).
- Throws MongoDB\Driver\Exception\AuthenticationException if authentication is needed and fails.
- Throws MongoDB\Driver\Exception\RuntimeException on other errors (e.g. invalid command, issuing a write command to a secondary).

### Changelog

Version | Description
--- | ---
PECL mongodb 1.4.4 | MongoDB\Driver\Exception\InvalidArgumentException will be thrown if the `"session"` option is used in combination with an unacknowledged write concern.
PECL mongodb 1.4.0 | The third parameter is now an `options` array. For backwards compatibility, this paramater will still accept a MongoDB\Driver\ReadPreference object.

### Notes

> Note: It is the caller's responsibility to ensure that the server is capable of executing the write operation. For example, executing a write operation on a secondary (excluding its "local" database) will fail.

### See Also

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