check-constraint

CONSTRAINT constraint-name
Names the check constraint. A constraint-name must not identify a constraint that was previously specified in the CREATE TABLE statement and must not identify a constraint that already exists at the current server.

If the clause is not specified, a unique constraint name is generated by the database manager.

CHECK (check-condition)
Defines a check constraint. At any time, the check-condition must be true or unknown for every row of the table.

The check-condition is a search-condition except:

For more information about search-condition, see Search conditions. For more information about check constraints involving LOB data types and expressions, see the Database Programming book.