Use passthrough mode when you want the client to have direct access to the capabilities of a DBMS target. The SQL dialect is for ODBC, not the actual DBMS dialect to which the ODBC driver is connected.
The access service performs virtually no SQL transformation. The passthrough mode converts carriage returns and line feeds. All other commands are passed directly to the ODBC driver, and the results are returned to the client.
In ECDA Option for ODBC, you can prepare multiple SQL statements in a single statement. When you do this, be sure to separate the statements with semicolons.