The define integrity statement creates an integrity constraint for the specified base table. Only the owner of a table is allowed to define integrities on the table. The integrity constraint you specify in the qual parameter must be true for the table at the time the define integrity statement is issued. If not, the DBMS Server displays an error message and does not create the integrity. If the constraint includes one or more columns that contain nulls, you must specify or is null in the qual parameter.

While executing, the define integrity statement takes out an exclusive lock on the table.