# SYSCONSTRAINTS system table

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

Parent topic: Derby system tables