Add docs for information_schema.CHECK_CONSTRAINTS (#14780)

pingcap · Sep 28, 2023 · 89fb4ed · 89fb4ed
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diff --git a/TOC-tidb-cloud.md b/TOC-tidb-cloud.md
@@ -511,6 +511,7 @@
       - INFORMATION_SCHEMA
         - [Overview](/information-schema/information-schema.md)
         - [`ANALYZE_STATUS`](/information-schema/information-schema-analyze-status.md)
+        - [`CHECK_CONSTRAINTS`](/information-schema/information-schema-check-constraints.md)
         - [`CLIENT_ERRORS_SUMMARY_BY_HOST`](/information-schema/client-errors-summary-by-host.md)
         - [`CLIENT_ERRORS_SUMMARY_BY_USER`](/information-schema/client-errors-summary-by-user.md)
         - [`CLIENT_ERRORS_SUMMARY_GLOBAL`](/information-schema/client-errors-summary-global.md)
@@ -616,4 +617,4 @@
   - [2021](/tidb-cloud/release-notes-2021.md)
   - [2020](/tidb-cloud/release-notes-2020.md)
 - Maintenance Notification
-  - [[2023-08-31] TiDB Cloud Console Maintenance Notification](/tidb-cloud/notification-2023-08-31-console-maintenance.md)
+  - [[2023-08-31] TiDB Cloud Console Maintenance Notification](/tidb-cloud/notification-2023-08-31-console-maintenance.md)
diff --git a/TOC.md b/TOC.md
@@ -894,6 +894,7 @@
       - INFORMATION_SCHEMA
         - [Overview](/information-schema/information-schema.md)
         - [`ANALYZE_STATUS`](/information-schema/information-schema-analyze-status.md)
+        - [`CHECK_CONSTRAINTS`](/information-schema/information-schema-check-constraints.md)
         - [`CLIENT_ERRORS_SUMMARY_BY_HOST`](/information-schema/client-errors-summary-by-host.md)
         - [`CLIENT_ERRORS_SUMMARY_BY_USER`](/information-schema/client-errors-summary-by-user.md)
         - [`CLIENT_ERRORS_SUMMARY_GLOBAL`](/information-schema/client-errors-summary-global.md)

diff --git a/information-schema/information-schema-check-constraints.md b/information-schema/information-schema-check-constraints.md
@@ -0,0 +1,52 @@
+---
+title: CHECK_CONSTRAINTS
+summary: Learn the `CHECK_CONSTRAINTS` INFORMATION_SCHEMA table.
+---
+
+# CHECK\_CONSTRAINTS
+
+The `CHECK_CONSTRAINTS` table provides information about [`CHECK` constraints](/constraints.md#check) on tables.
+
+```sql
+USE INFORMATION_SCHEMA;
+DESC CHECK_CONSTRAINTS;
+```
+
+The output is as follows:
+
+```sql
++--------------------+-------------+------+-----+---------+-------+
+| Field              | Type        | Null | Key | Default | Extra |
++--------------------+-------------+------+-----+---------+-------+
+| CONSTRAINT_CATALOG | varchar(64) | NO   |     | NULL    |       |
+| CONSTRAINT_SCHEMA  | varchar(64) | NO   |     | NULL    |       |
+| CONSTRAINT_NAME    | varchar(64) | NO   |     | NULL    |       |
+| CHECK_CLAUSE       | longtext    | NO   |     | NULL    |       |
++--------------------+-------------+------+-----+---------+-------+
+4 rows in set (0.00 sec)
+```
+
+The following example adds a `CHECK` constraint using the `CREATE TABLE` statement:
+
+```sql
+CREATE TABLE test.t1 (id INT PRIMARY KEY, CHECK (id%2 = 0));
+SELECT * FROM CHECK_CONSTRAINTS\G
+```
+
+The output is as follows:
+
+```sql
+*************************** 1. row ***************************
+CONSTRAINT_CATALOG: def
+ CONSTRAINT_SCHEMA: test
+   CONSTRAINT_NAME: t1_chk_1
+      CHECK_CLAUSE: (`id` % 2 = 0)
+1 row in set (0.00 sec)
+```
+
+Fields in the `CHECK_CONSTRAINTS` table are described as follows:
+
+* `CONSTRAINT_CATALOG`: The catalog of the constraint, which is always `def`.
+* `CONSTRAINT_SCHEMA`: The schema of the constraint.
+* `CONSTRAINT_NAME`: The name of the constraint.
+* `CHECK_CLAUSE`: The clause of the check constraint.