# Information Schema CHECK\_CONSTRAINTS Table The [Information Schema](/docs/server/reference/system-tables/information-schema.md) `CHECK_CONSTRAINTS` table stores metadata about the [constraints](/docs/server/reference/sql-statements/data-definition/constraint.md) defined for tables in all databases. It contains the following columns: | Column | Description | | ------------------- | ---------------------------------------------------------------------------------------------------------------------------------------- | | CONSTRAINT\_CATALOG | Always contains the string 'def'. | | CONSTRAINT\_SCHEMA | Database name. | | CONSTRAINT\_NAME | Constraint name. | | TABLE\_NAME | Table name. | | LEVEL | Type of the constraint ('Column' or 'Table'). From [MariaDB 10.5.10](/docs/release-notes/community-server/old-releases/10.5/10.5.10.md). | | CHECK\_CLAUSE | Constraint clause. | ## Example A table with a numeric table check constraint and with a default check constraint name: ```sql CREATE TABLE t ( a INT, CHECK (a>10)); ``` To see check constraint call `check_constraints` table from [information schema](/docs/server/reference/system-tables/information-schema.md). ```sql SELECT * FROM INFORMATION_SCHEMA.CHECK_CONSTRAINTS\G ``` ```sql *************************** 1. row *************************** CONSTRAINT_CATALOG: def CONSTRAINT_SCHEMA: test CONSTRAINT_NAME: CONSTRAINT_1 TABLE_NAME: t CHECK_CLAUSE: `a` > 10 ``` A new table check constraint called `a_upper`: ```sql ALTER TABLE t ADD CONSTRAINT a_upper CHECK (a<100); ``` ```sql SELECT * FROM INFORMATION_SCHEMA.CHECK_CONSTRAINTS\G ``` ```sql *************************** 1. row *************************** CONSTRAINT_CATALOG: def CONSTRAINT_SCHEMA: test CONSTRAINT_NAME: CONSTRAINT_1 TABLE_NAME: t CHECK_CLAUSE: `a` > 10 *************************** 2. row *************************** CONSTRAINT_CATALOG: def CONSTRAINT_SCHEMA: test CONSTRAINT_NAME: a_upper TABLE_NAME: t CHECK_CLAUSE: `a` < 100 ``` A new table `tt` with a field check constraint called `b` , as well as a table check constraint called `b_upper`: ```sql CREATE TABLE tt(b INT CHECK(b>0),CONSTRAINT b_upper CHECK(b<50)); SELECT * FROM INFORMATION_SCHEMA.CHECK_CONSTRAINTS; +--------------------+-------------------+-----------------+------------+--------------+ | CONSTRAINT_CATALOG | CONSTRAINT_SCHEMA | CONSTRAINT_NAME | TABLE_NAME | CHECK_CLAUSE | +--------------------+-------------------+-----------------+------------+--------------+ | def | test | b | tt | `b` > 0 | | def | test | b_upper | tt | `b` < 50 | | def | test | CONSTRAINT_1 | t | `a` > 10 | | def | test | a_upper | t | `a` < 100 | +--------------------+-------------------+-----------------+------------+--------------+ ``` *Note:* The name of the field constraint is the same as the field name. After dropping the default table constraint called `CONSTRAINT_1`: ```sql ALTER TABLE t DROP CONSTRAINT CONSTRAINT_1; SELECT * FROM INFORMATION_SCHEMA.CHECK_CONSTRAINTS; +--------------------+-------------------+-----------------+------------+--------------+ | CONSTRAINT_CATALOG | CONSTRAINT_SCHEMA | CONSTRAINT_NAME | TABLE_NAME | CHECK_CLAUSE | +--------------------+-------------------+-----------------+------------+--------------+ | def | test | b | tt | `b` > 0 | | def | test | b_upper | tt | `b` < 50 | | def | test | a_upper | t | `a` < 100 | +--------------------+-------------------+-----------------+------------+--------------+ ``` Trying to insert invalid arguments into table `t` and `tt` generates an error. ```sql INSERT INTO t VALUES (10),(20),(100); ERROR 4025 (23000): CONSTRAINT `a_upper` failed for `test`.`t` INSERT INTO tt VALUES (10),(-10),(100); ERROR 4025 (23000): CONSTRAINT `b` failed for `test`.`tt` INSERT INTO tt VALUES (10),(20),(100); ERROR 4025 (23000): CONSTRAINT `b_upper` failed for `test`.`tt` ``` {% hint style="info" %} The following statement can be performed from MariaDB 10.5.10. {% endhint %} ```sql CREATE TABLE majra(CHECK(x>0), x INT, y INT CHECK(y < 0), z INT, CONSTRAINT z CHECK(z>0), CONSTRAINT xyz CHECK(x<10 AND y<10 AND z<10)); Query OK, 0 rows affected (0.036 sec) SHOW CREATE TABLE majra; +-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Table | Create Table | +-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | majra | CREATE TABLE `majra` ( `x` int(11) DEFAULT NULL, `y` int(11) DEFAULT NULL CHECK (`y` < 0), `z` int(11) DEFAULT NULL, CONSTRAINT `CONSTRAINT_1` CHECK (`x` > 0), CONSTRAINT `z` CHECK (`z` > 0), CONSTRAINT `xyz` CHECK (`x` < 10 AND `y` < 10 AND `z` < 10) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 | +-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.000 sec) SELECT * FROM information_schema.check_constraints WHERE table_name='majra'; +--------------------+-------------------+------------+-----------------+--------+------------------------------------+ | CONSTRAINT_CATALOG | CONSTRAINT_SCHEMA | TABLE_NAME | CONSTRAINT_NAME | LEVEL | CHECK_CLAUSE | +--------------------+-------------------+------------+-----------------+--------+------------------------------------+ | def | test | majra | y | Column | `y` < 0 | | def | test | majra | CONSTRAINT_1 | Table | `x` > 0 | | def | test | majra | z | Table | `z` > 0 | | def | test | majra | xyz | Table | `x` < 10 and `y` < 10 and `z` < 10 | +--------------------+-------------------+------------+-----------------+--------+------------------------------------+ 4 rows in set (0.001 sec) ``` *This page is licensed: CC BY-SA / Gnu FDL* {% @marketo/form formId="4316" %} --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://mariadb.com/docs/server/reference/system-tables/information-schema/information-schema-tables/information-schema-check_constraints-table.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.