dbcc-checkconstraints-transact-sql.md

description	DBCC CHECKCONSTRAINTS (Transact-SQL)
title	DBCC CHECKCONSTRAINTS (Transact-SQL)
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ms.date	11/14/2017
ms.prod	sql
ms.prod_service	sql-database
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ms.technology	t-sql
ms.topic	language-reference
f1_keywords	DBCC CHECKCONSTRAINTS DBCC_CHECKCONSTRAINTS_TSQL CHECKCONSTRAINTS CHECKCONSTRAINTS_TSQL
dev_langs	TSQL
helpviewer_keywords	DBCC CHECKCONSTRAINTS statement consistency [SQL Server], constraints checking constraint consistency constraints [SQL Server], consistency checks integrity [SQL Server], constraints
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author	pmasl
ms.author	umajay

DBCC CHECKCONSTRAINTS (Transact-SQL)

[!INCLUDE SQL Server SQL Database Azure SQL Managed Instance]

Checks the integrity of a specified constraint or all constraints on a specified table in the current database.

Transact-SQL Syntax Conventions

Syntax

DBCC CHECKCONSTRAINTS  
[   
    (   
    table_name | table_id | constraint_name | constraint_id   
    )  
]  
    [ WITH   
    [ { ALL_CONSTRAINTS | ALL_ERRORMSGS } ]  
    [ , ] [ NO_INFOMSGS ]   
    ]  

[!INCLUDEsql-server-tsql-previous-offline-documentation]

Arguments

table_name | table_id | constraint_name | constraint_id
Is the table or constraint to be checked. When table_name or table_id is specified, all enabled constraints on that table are checked. When constraint_name or constraint_id is specified, only that constraint is checked. If neither a table identifier nor a constraint identifier is specified, all enabled constraints on all tables in the current database are checked.
A constraint name uniquely identifies the table to which it belongs. For more information, see Database Identifiers.

WITH
Enables options to be specified.

ALL_CONSTRAINTS
Checks all enabled and disabled constraints on the table if the table name is specified or if all tables are checked; otherwise, checks only the enabled constraint. ALL_CONSTRAINTS has no effect when a constraint name is specified.

ALL_ERRORMSGS
Returns all rows that violate constraints in the table that is checked. The default is the first 200 rows.

NO_INFOMSGS
Suppresses all informational messages.

Remarks

DBCC CHECKCONSTRAINTS constructs and executes a query for all FOREIGN KEY constraints and CHECK constraints on a table.

For example, a foreign key query is of the following form:

SELECT <columns>  
FROM <table_being_checked> LEFT JOIN <referenced_table>  
    ON <table_being_checked.fkey1> = <referenced_table.pkey1>   
    AND <table_being_checked.fkey2> = <referenced_table.pkey2>  
WHERE <table_being_checked.fkey1> IS NOT NULL   
    AND <referenced_table.pkey1> IS NULL  
    AND <table_being_checked.fkey2> IS NOT NULL  
    AND <referenced_table.pkey2> IS NULL  

The query data is stored in a temp table. After all requested tables or constraints have been checked, the result set is returned. DBCC CHECKCONSTRAINTS checks the integrity of FOREIGN KEY and CHECK constraints but does not check the integrity of the on-disk data structures of a table. These data structure checks can be performed by using DBCC CHECKDB and DBCC CHECKTABLE.

Applies to: [!INCLUDEsssql16-md] and later

If table_name or table_id is specified and it is enabled for system versioning, DBCC CHECKCONSTRAINTS also performs temporal data consistency checks on the specified table. When NO_INFOMSGS is not specified, this command will return each consistency violation in the output on a separate line. The format of the output will be ([pkcol1], [pkcol2]..) = (<pkcol1_value>, <pkcol2_value>...) AND <what is wrong with temporal table record>.

Check	Additional info in output if check failed
PeriodEndColumn ≥ PeriodStartColumn (current)	[sys_end] = '{0}' AND MAX(DATETIME2) = '9999-12-31 23:59:59.99999'
PeriodEndColumn ≥ PeriodStartColumn (current, history)	[sys_start] = '{0}' AND [sys_end] = '{1}'
PeriodStartColumn < current_utc_time (current)	[sys_start] = '{0}' AND SYSUTCTIME
PeriodEndColumn < current_utc_time (history)	[sys_end] = '{0}' AND SYSUTCTIME
Overlaps	(sys_start1, sys_end1) , (sys_start2, sys_end2) for two overlapping records. If there are more than 2 overlapping records, output will have multiple rows each showing a pair of overlaps.

There is no way to specify constraint_name or constraint_id in order to run only temporal consistency checks.

Result Sets

DBCC CHECKCONSTRAINTS return a rowset with the following columns.

Column name	Data type	Description
Table Name	varchar	Name of the table.
Constraint Name	varchar	Name of the constraint that is violated.
Where	varchar	Column value assignments that identify the row or rows violating the constraint. The value in this column can be used in a WHERE clause of a SELECT statement querying for rows that violate the constraint.

Permissions

Requires membership in the sysadmin fixed server role or the db_owner fixed database role.

Examples

A. Checking a table

The following example checks the constraint integrity of the table Table1 in the AdventureWorks database.

USE AdventureWorks2012;  
GO  
CREATE TABLE Table1 (Col1 INT, Col2 CHAR(30));  
GO  
INSERT INTO Table1 VALUES (100, 'Hello');  
GO  
ALTER TABLE Table1 WITH NOCHECK ADD CONSTRAINT chkTab1 CHECK (Col1 > 100);  
GO  
DBCC CHECKCONSTRAINTS(Table1);  
GO  

B. Checking a specific constraint

The following example checks the integrity of the CK_ProductCostHistory_EndDate constraint.

USE AdventureWorks2012;  
GO  
DBCC CHECKCONSTRAINTS ('Production.CK_ProductCostHistory_EndDate');  
GO  

C. Checking all enabled and disabled constraints on all tables

The following example checks the integrity of all enabled and disabled constraints on all tables in the current database.

DBCC CHECKCONSTRAINTS WITH ALL_CONSTRAINTS;  
GO  

See Also

DBCC CHECKDB (Transact-SQL)
DBCC CHECKTABLE (Transact-SQL)
DBCC (Transact-SQL)