OLE DB Commands (SQL Server Compact Edition)

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In OLE DB, a command object is used to execute provider-specific text commands. These are similar to SQL statements.

Using Commands

The basic steps for using commands in OLE DB are:

  1. A command object is created from an existing session object using IDBCreateCommand::CreateCommand.
  2. The command text for the query is specified using ICommandText.
    The command syntax supported by the OLE DB Provider for Microsoft SQL Server 2005 Compact Edition (SQL Server Compact Edition) is specified as DBGUID_SQL. DBGUID_SQL syntax is primarily SQL-92 syntax with ODBC escape sequences.
  3. The command is executed using ICommand::Execute.

SQL Server Compact Edition supports a subset of the SQL Server Transact-SQL query grammar. Queries that can typically be run on SQL Server Compact Edition can also run on SQL Server 2000; however, many of the features of Transact-SQL are absent from SQL Server Compact Edition and only a single SQL statement can be executed in a command.

SQL Server Compact Edition supports parameterized queries in which parameters are delimited with the question mark (?) character. It also supports named parameterized queries.

For more information about the query grammar supported by SQL Server Compact Edition, see SQL Reference (SQL Server Compact Edition).

Preparing Commands

To execute a query, the Database Engine must first parse, compile, and optimize the SQL statement. Frequently, this work can be completed one time if the command is to be executed multiple times, potentially saving time. If clients expect to run a query more than one time, we recommend that the command be prepared one time. Then, call Execute multiple times. This should maximize performance by avoiding query recompilation. Commands can be prepared before they are executed by calling ICommandPrepare::Prepare. This is equivalent to compiling the command.

Examples

For an example of creating and executing commands using the OLE DB provider for SQL Server Compact Edition, see the example in OLE DB Parameters (SQL Server Compact Edition).