Executes the current work queue. If $force is specified as true, the changes specified in the queue will be processed even if the current request should be considered idempotent or safe, such as a HTTP 'GET'.
Returns true on success, or false on error. Additional information may be available using getLastError() and getLastErrNo().
Clears the work queue without processing.
Adds an SQL/DDL statement to the work queue. This can be useful in special circumstances. Be aware that no processing is performed on the SQL -- it is used as supplied. No attempt is made to insure portability or compatibility among different database platforms.