如何在SQL Server中使用“WITH NOCHECK”列出所有外键

Question

有谁知道一个查询列出了应用了“WITH NOCHECK”说明的数据库中的所有外键吗？ （去除它们将提高性能和稳定性）。

Answer 1

下面将在目前的返回外键的名称数据库与NOCHECK

残疾人即对于SQL Server 2005/2008：

select * from sys.foreign_keys where is_disabled=1 

---

有大约不受信任禁用&之间的差别，答案了一些讨论。 以下内容解释了差异 下面是一些代码，用于说明is_disabled &之间的区别是不可信的。

-- drop table t1 
-- drop table t2 
create table t1(i int not null, fk int not null) 
create table t2(i int not null) 
-- create primary key on t2 
alter table t2 
add constraint pk_1 primary key (i) 
-- create foriegn key on t1 
alter table t1 
add constraint fk_1 foreign key (fk) 
    references t2 (i) 
--insert some records 
insert t2 values(100) 
insert t2 values(200) 
insert t2 values(300) 
insert t2 values(400) 
insert t2 values(500) 
insert t1 values(1,100) 
insert t1 values(2,100) 
insert t1 values(3,500) 
insert t1 values(4,500) 
---------------------------- 
-- 1. enabled and trusted 
select name,is_disabled,is_not_trusted from sys.foreign_keys 
GO 

-- 2. disable the constraint 
alter table t1 NOCHECK CONSTRAINT fk_1 
select name,is_disabled,is_not_trusted from sys.foreign_keys 
GO 

-- 3. re-enable constraint, data isnt checked, so not trusted. 
-- this means the optimizer will still have to check the column 
alter table t1 CHECK CONSTRAINT fk_1 
select name,is_disabled,is_not_trusted from sys.foreign_keys 
GO 

--4. drop the foreign key constraint & re-add 
-- it making sure its checked 
-- constraint is then enabled and trusted 
alter table t1 DROP CONSTRAINT fk_1 
alter table t1 WITH CHECK 
add constraint fk_1 foreign key (fk) 
    references t2 (i) 
select name,is_disabled,is_not_trusted from sys.foreign_keys 
GO 


--5. drop the foreign key constraint & add but dont check 
-- constraint is then enabled, but not trusted 
alter table t1 DROP CONSTRAINT fk_1 
alter table t1 WITH NOCHECK 
add constraint fk_1 foreign key (fk) 
    references t2 (i) 
select name,is_disabled,is_not_trusted from sys.foreign_keys 
GO 

is_disabled手段约束被禁用

isnottrusted意味着SQL Server不相信，列已针对外键表检查。

因此不能假定重新启用外键约束将被优化。为确保优化器信任该列，最好放弃外键约束&使用WITH CHECK选项（4.）

Answer 2

WITH NOCHECK应该只适用于FK的暂时性，或者当您的链接文章指出它们对优化程序无用时。从BOL：

的查询优化器不会考虑与 NOCHECK定义 约束。这些约束将被忽略 ，直到通过使用 重新启用它们为止。ALTER TABLE表CHECK CONSTRAINT ALL。

这会找出所有的外键（在WITH NOCHECK位工作...）

SELECT C.TABLE_CATALOG [PKTABLE_QUALIFIER], 
     C.TABLE_SCHEMA [PKTABLE_OWNER], 
     C.TABLE_NAME [PKTABLE_NAME], 
     KCU.COLUMN_NAME [PKCOLUMN_NAME], 
     C2.TABLE_CATALOG [FKTABLE_QUALIFIER], 
     C2.TABLE_SCHEMA [FKTABLE_OWNER], 
     C2.TABLE_NAME [FKTABLE_NAME], 
     KCU2.COLUMN_NAME [FKCOLUMN_NAME], 
     RC.UPDATE_RULE, 
     RC.DELETE_RULE, 
     C.CONSTRAINT_NAME [FK_NAME], 
     C2.CONSTRAINT_NAME [PK_NAME], 
     CAST(7 AS SMALLINT) [DEFERRABILITY] 
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS C 
     INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE KCU 
     ON C.CONSTRAINT_SCHEMA = KCU.CONSTRAINT_SCHEMA 
      AND C.CONSTRAINT_NAME = KCU.CONSTRAINT_NAME 
     INNER JOIN INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS RC 
     ON C.CONSTRAINT_SCHEMA = RC.CONSTRAINT_SCHEMA 
      AND C.CONSTRAINT_NAME = RC.CONSTRAINT_NAME 
     INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS C2 
     ON RC.UNIQUE_CONSTRAINT_SCHEMA = C2.CONSTRAINT_SCHEMA 
      AND RC.UNIQUE_CONSTRAINT_NAME = C2.CONSTRAINT_NAME 
     INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE KCU2 
     ON C2.CONSTRAINT_SCHEMA = KCU2.CONSTRAINT_SCHEMA 
      AND C2.CONSTRAINT_NAME = KCU2.CONSTRAINT_NAME 
      AND KCU.ORDINAL_POSITION = KCU2.ORDINAL_POSITION 
WHERE C.CONSTRAINT_TYPE = 'FOREIGN KEY' 

Ref。

顺便说一句，这两个SQL Server 2000和2005年，但如果任何数据违反使用约束检查：

DBCC CHECKCONSTRAINTS (table_name) 

Answer 3

SELECT * FROM sys.foreign_keys AS f Where Is_Not_Trusted = 1 

Answer 4

重新创建它以下代码将检索标记为'WITH NOCHECK'的所有外键，然后使用ALTER语句来解决这些问题了：

-- configure cursor on all FKs with "WITH NOCHECK" 
DECLARE UntrustedForeignKeysCursor CURSOR STATIC FOR 
    SELECT f.name, 
      t.name 
    FROM sys.foreign_keys AS f 
      LEFT JOIN sys.tables AS t 
       ON f.parent_object_id = t.object_id 
    Where Is_Not_Trusted = 1 
OPEN UntrustedForeignKeysCursor 

-- loop through the untrusted FKs 
DECLARE @FKName varchar(100) 
DECLARE @TableName varchar(100) 
FETCH NEXT FROM UntrustedForeignKeysCursor INTO @FKName, @TableName 
WHILE @@FETCH_STATUS = 0 
BEGIN 

    -- Rebuild the FK constraint WITH CHECK 
    EXEC ('ALTER TABLE ' + @TableName + ' WITH CHECK CHECK CONSTRAINT ' + @FKName) 

    -- get next user 
    FETCH NEXT FROM UntrustedForeignKeysCursor INTO @FKName, @TableName 

END 

-- cleanup 
CLOSE UntrustedForeignKeysCursor 

Answer 5

下面的脚本将生成ALTER语句都将检查现有数据，并防止对那些目前没有可信的（“WITH NOCHECK”）外键的任何新的违规行为。

在SQL Server Management Studio中执行它以生成脚本，然后将它们复制到查询窗口中以执行它们。

select 
    'alter table ' + quotename(s.name) + '.' + quotename(t.name) + ' with check check constraint ' + fk.name +';' 
from 
    sys.foreign_keys fk 
inner join 
    sys.tables t 
on 
    fk.parent_object_id = t.object_id 
inner join 
    sys.schemas s 
on 
    t.schema_id = s.schema_id 
where 
    fk.is_not_trusted = 1 

Answer 6

我知道这是一个老问题，有一些老的答案有一些很好的信息。不过，我只是想分享，我一直在使用相当多的不同的数据库来解决这一问题方面为我们的脚本：

-- Foreign Keys 
SELECT 'ALTER TABLE ' + o.name + ' WITH CHECK CHECK CONSTRAINT ' + i.name + ';' AS AlterStatement 
from sys.foreign_keys i 
INNER JOIN sys.objects o ON i.parent_object_id = o.object_id 
INNER JOIN sys.schemas s ON o.schema_id = s.schema_id 
WHERE i.is_not_trusted = 1 AND i.is_not_for_replication = 0; 
GO 

-- Constraints 
SELECT 'ALTER TABLE ' + o.name + ' WITH CHECK CHECK CONSTRAINT ' + i.name + ';' AS AlterStatement 
from sys.check_constraints i 
INNER JOIN sys.objects o ON i.parent_object_id = o.object_id 
INNER JOIN sys.schemas s ON o.schema_id = s.schema_id 
WHERE i.is_not_trusted = 1 AND i.is_not_for_replication = 0 AND i.is_disabled = 0; 
GO 

，这将产生ALTER语句的集合，以解决这个问题“NOCHECK”问题与外键和约束。这是基于Brent Ozar提供的一些查询，但是我为了我的目的和易用性而进行了调整。这可以很容易地调整与UNION使其成为一个单一的查询。

仅供参考，我在Azure SQL数据库环境中专门使用了它。我不确定在旧版本的SQL Server上是否存在限制，但它在Azure中效果很好。