Variable constraint messages
You can use variables in constraint messages. In this way error messages and information messages issued by constraints can be made clearer and are more informative to the user.
Variables in constraint messages are surrounded by angle brackets (<>).
These variables can refer to:
•Values of columns used in the constraint.
•Values of alias names for columns used in the constraint.
•Old values of columns used in the constraint.
•Parameter values of methods used in the constraint.
•Meta information of columns and tables, like table names, object names, and prompts.
Angle brackets (<>) can also be used in other places in constraint messages. Only when one of the pre-defined variables is enclosed will it be replaced.