The SYSFOREIGNKEYS table describes the information specific to foreign key constraints in the current database.
Derby generates a backing index for each foreign key constraint. The name of this index is the same as SYSFOREIGNKEYS.CONGLOMERATEID.
The following table shows the contents of the SYSFOREIGNKEYS system table.
| Column Name | Type | Length | Nullable | Contents |
|---|---|---|---|---|
| CONSTRAINTID | CHAR | 36 | false | Unique identifier for the foreign key constraint (join with SYSCONSTRAINTS.CONSTRAINTID) |
| CONGLOMERATEID | CHAR | 36 | false | Unique identifier for index backing up the foreign key constraint (join with SYSCONGLOMERATES. CONGLOMERATEID) |
| KEYCONSTRAINTID | CHAR | 36 | false | Unique identifier for the primary key or unique constraint referenced by this foreign key (SYSKEYS.CONSTRAINTID or SYSCONSTRAINTS.CONSTRAINTID) |
| DELETERULE | CHAR | 1 | false | 'R' for NO ACTION (default), 'S' for RESTRICT, 'C' for CASCADE, 'U' for SET NULL |
| UPDATERULE | CHAR | 1 | false | 'R' for NO ACTION (default), 'S' for RESTRICT |