Describes the information common to all types of constraints within
the current database (currently, this includes primary key, unique, foreign
key, and check constraints).   
| Column Name | Type | Length | Nullable | Contents | 
| CONSTRAINTID | CHAR | 36 | false | unique identifier for constraint | 
| TABLEID | CHAR | 36 | false | identifier for table (join with SYSTABLES.TABLEID) | 
| CONSTRAINTNAME | VARCHAR | 128 | false | constraint name (internally generated if not specified
by user) | 
| TYPE | CHAR | 1 | false | P (primary key), U (unique), C (check),
or F (foreign key) | 
| SCHEMAID | CHAR | 36 | false | identifier for schema that the constraint belongs to (join
with SYSSCHEMAS.SCHEMAID) | 
| STATE | CHAR | 1 | false | E for enabled, D for disabled | 
| REFERENCECOUNT | INTEGER | 1 | false | the count of the number of foreign key constraints that
reference this constraint; this number can be greater than zero only for PRIMARY
KEY and UNIQUE constraints |