The view key_column_usage identifies all columns
in the current database that are restricted by some unique, primary
key, or foreign key constraint. Check constraints are not included
in this view. Only those columns are shown that the current user
has access to, by way of being the owner or having some privilege.
Table 32-19. key_column_usage Columns
| Name | Data Type | Description |
|---|
| 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 that contains the
column that is restricted by some constraint (always the
current database)
|
| table_schema | sql_identifier | Name of the schema that contains the table that contains the
column that is restricted by some constraint
|
| table_name | sql_identifier | Name of the table that contains the column that is restricted
by some constraint
|
| column_name | sql_identifier | Name of the column that is restricted by some constraint
|
| ordinal_position | cardinal_number | Ordinal position of the column within the constraint key (count
starts at 1)
|
| position_in_unique_constraint | cardinal_number | Not yet implemented
|