Purpose
The information_schema.KEY_COLUMN_USAGE view provides information about constraints on columns.
Note
This view is introduced since OceanBase Database V1.4.
Columns
Column |
Type |
Nullable? |
Description |
|---|---|---|---|
| CONSTRAINT_CATALOG | varchar(3) | NO | The name of the catalog to which the table containing the column belongs. The value is always def. |
| CONSTRAINT_SCHEMA | varchar(128) | NO | The name of the database. |
| CONSTRAINT_NAME | varchar(7) | NO | The name of the constraint. The value is PRIMARY, the column name, or the foreign key name. |
| TABLE_CATALOG | varchar(3) | NO | The name of the catalog to which the table belongs. |
| TABLE_SCHEMA | varchar(128) | NO | The name of the database. |
| TABLE_NAME | varchar(256) | NO | The name of the table. |
| COLUMN_NAME | varchar(128) | NO | The name of the column. |
| ORDINAL_POSITION | bigint(20) | NO | The serial number of the column within the table. |
| POSITION_IN_UNIQUE_CONSTRAINT | null | NO | The value is NULL for unique and primary-key constraints. For foreign-key constraints, the value is the ordinal position in key of the table that is being referenced. |
| REFERENCED_TABLE_SCHEMA | varchar(128) | NO | The name of the database referenced by the constraint. |
| REFERENCED_TABLE_NAME | varchar(256) | NO | The name of the table referenced by the constraint. |
| REFERENCED_COLUMN_NAME | varchar(128) | NO | The name of the column referenced by the constraint. |