The view check_constraints contains all check
   constraints, either defined on a table or on a domain, that are
   owned by a currently enabled role.  (The owner of the table or
   domain is the owner of the constraint.)
  
Table 32-6. check_constraints Columns
| Name | Data Type | Description | 
|---|
| constraint_catalog | sql_identifier | Name of the database containing the constraint (always the current database) | 
| constraint_schema | sql_identifier | Name of the schema containing the constraint | 
| constraint_name | sql_identifier | Name of the constraint | 
| check_clause | character_data | The check expression of the check constraint |