> For the complete documentation index, see [llms.txt](https://mariadb.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mariadb.com/docs/server/reference/system-tables/information-schema/information-schema-tables/information-schema-table_constraints-table.md).

# Information Schema TABLE\_CONSTRAINTS Table

The [Information Schema](/docs/server/reference/system-tables/information-schema.md) `TABLE_CONSTRAINTS` table contains information about tables that have [constraints](/docs/server/reference/sql-statements/data-definition/constraint.md).

It has the following columns:

| Column              | Description                                                           |
| ------------------- | --------------------------------------------------------------------- |
| CONSTRAINT\_CATALOG | Always def.                                                           |
| CONSTRAINT\_SCHEMA  | Database name containing the constraint.                              |
| CONSTRAINT\_NAME    | Constraint name.                                                      |
| TABLE\_SCHEMA       | Database name.                                                        |
| TABLE\_NAME         | Table name.                                                           |
| CONSTRAINT\_TYPE    | Type of constraint; one of UNIQUE, PRIMARY KEY, FOREIGN KEY or CHECK. |

The [REFERENTIAL\_CONSTRAINTS](/docs/server/reference/system-tables/information-schema/information-schema-tables/information-schema-referential_constraints-table.md) table has more information about foreign keys.

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