ASA SQL User's Guide
Ensuring Data Integrity
All the information about database integrity checks and rules is held in the following system tables:
| System table | Description |
|---|---|
| SYS.SYSTABLE | The view_def column of SYS.SYSTABLE holds CHECK constraints. For views, the view_def holds the CREATE VIEW command that created the view. You can check whether a particular table is a base table or a view by looking at the table_type column, which is BASE or VIEW. |
| SYS.SYSTRIGGER |
SYS.SYSTRIGGER holds referential integrity actions.
The referential_action column holds a single character indicating whether the action is cascade (C), delete (D), set null (N), or restrict (R). The event column holds a single character specifying the event that causes the action to occur: insert, delete (A), insert, update (B), update (C), a delete (D), delete, update (E),insert (I), update (U), insert, delete, update (M). The trigger_time column shows whether the action occurs after (A) or before (B) the triggering event. |
| SYS.SYSFOREIGNKEYS | This view presents the foreign key information from the two tables SYS.SYSFOREIGNKEY and SYS.SYSFKCOL in a more readable format. |
| SYS.SYSCOLUMNS | This view presents the information from the SYS.SYSCOLUMN table in a more readable format. It includes default settings and primary key information for columns. |
For more information about the contents of each system table, see System Tables. You can use Sybase Central or Interactive SQL to browse these tables and views.