Logical Operators

You can create MDL scripts that check to see whether or not a component or subcomponent record meets certain conditions before executing a command.

Operator	Syntax	Description
IF EXISTS	ALTER component_type_name IF EXISTS component_name	If the component type exists, execute the MDL command.
IF NOT EXISTS	RECREATE component_type_name IF NOT EXISTS component_name	If the component type does not exist, execute the MDL command.