| constraint_catalog | sql_identifier | Name of the database that contains the constraint (always the current database) | 
| constraint_schema | sql_identifier | Name of the schema that contains the constraint | 
| constraint_name | sql_identifier | Name of the constraint | 
| table_catalog | sql_identifier | Name of the database that contains the table (always the current database) | 
| table_schema | sql_identifier | Name of the schema that contains the table | 
| table_name | sql_identifier | Name of the table | 
| constraint_type | character_data | Type of the constraint: CHECK,
       FOREIGN KEY, PRIMARY KEY,
       or UNIQUE | 
| is_deferrable | character_data | YES if the constraint is deferrable, NO if not | 
| initially_deferred | character_data | YES if the constraint is deferrable and initially deferred, NO if not |