SQL Server支持禁用和启用外键约束吗?还是我唯一的选择就是放弃这些限制，然后重新创造这些限制?
(摘自http://www.sqljunkies.com/WebLog/roman/archive/2005/01/30/7037.aspx， 现在存档在时光倒流机中)
Foreign key constraints and check constraint are very useful for enforcing data integrity and business rules. There are certain scenarios though where it is useful to temporarily turn them off because their behavior is either not needed or could do more harm than good. I sometimes disable constraint checking on tables during data loads from external sources or when I need to script a table drop/recreate with reloading the data back into the table. I usually do it in scenarios where I don't want a time consuming process to fail because one or a few of many million rows have bad data in it. But I always turn the constraints back on once the process is finished and also in some cases I run data integrity checks on the imported data.
如果禁用外键约束，则可以插入父表中不存在的值。如果禁用检查约束，则可以将值放入列中，就像检查约束不存在一样。下面是禁用和启用表约束的一些例子:
——禁用所有表约束 修改表MyTable NOCHECK约束 ——启用所有表约束 修改MyTable，检查检查约束全部 ——禁用单个约束 修改表MyTable NOCHECK约束 ——启用单一约束 ALTER TABLE MyTable WITH CHECK CHECK CONSTRAINT MyConstraint
如果你想禁用数据库中的所有约束，只需运行以下代码:
-- disable all constraints
EXEC sp_MSforeachtable "ALTER TABLE ? NOCHECK CONSTRAINT all"
要将它们重新打开，运行:(打印当然是可选的，它只是列出表)
-- enable all constraints
exec sp_MSforeachtable @command1="print '?'", @command2="ALTER TABLE ? WITH CHECK CHECK CONSTRAINT all"
我发现它在将数据从一个数据库填充到另一个数据库时很有用。这是比放弃约束更好的方法。正如您所提到的，当删除数据库中的所有数据并重新填充它时(例如在测试环境中)，它非常方便。
如果您正在删除所有数据，您可能会发现这个解决方案是有用的。
有时禁用所有触发器也很方便，你可以在这里看到完整的解决方案。
SQL-92标准允许将约束声明为DEFERRABLE，以便在事务范围内(隐式或显式)延迟它。遗憾的是，SQL Server仍然缺少这个SQL-92功能。
对我来说，将约束更改为NOCHECK类似于动态更改数据库结构——删除约束当然是这样——这是需要避免的(例如，用户需要增加特权)。
--Drop and Recreate Foreign Key Constraints
SET NOCOUNT ON
DECLARE @table TABLE(
RowId INT PRIMARY KEY IDENTITY(1, 1),
ForeignKeyConstraintName NVARCHAR(200),
ForeignKeyConstraintTableSchema NVARCHAR(200),
ForeignKeyConstraintTableName NVARCHAR(200),
ForeignKeyConstraintColumnName NVARCHAR(200),
PrimaryKeyConstraintName NVARCHAR(200),
PrimaryKeyConstraintTableSchema NVARCHAR(200),
PrimaryKeyConstraintTableName NVARCHAR(200),
PrimaryKeyConstraintColumnName NVARCHAR(200)
)
INSERT INTO @table(ForeignKeyConstraintName, ForeignKeyConstraintTableSchema, ForeignKeyConstraintTableName, ForeignKeyConstraintColumnName)
SELECT
U.CONSTRAINT_NAME,
U.TABLE_SCHEMA,
U.TABLE_NAME,
U.COLUMN_NAME
FROM
INFORMATION_SCHEMA.KEY_COLUMN_USAGE U
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS C
ON U.CONSTRAINT_NAME = C.CONSTRAINT_NAME
WHERE
C.CONSTRAINT_TYPE = 'FOREIGN KEY'
UPDATE @table SET
PrimaryKeyConstraintName = UNIQUE_CONSTRAINT_NAME
FROM
@table T
INNER JOIN INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS R
ON T.ForeignKeyConstraintName = R.CONSTRAINT_NAME
UPDATE @table SET
PrimaryKeyConstraintTableSchema = TABLE_SCHEMA,
PrimaryKeyConstraintTableName = TABLE_NAME
FROM @table T
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS C
ON T.PrimaryKeyConstraintName = C.CONSTRAINT_NAME
UPDATE @table SET
PrimaryKeyConstraintColumnName = COLUMN_NAME
FROM @table T
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE U
ON T.PrimaryKeyConstraintName = U.CONSTRAINT_NAME
--SELECT * FROM @table
--DROP CONSTRAINT:
SELECT
'
ALTER TABLE [' + ForeignKeyConstraintTableSchema + '].[' + ForeignKeyConstraintTableName + ']
DROP CONSTRAINT ' + ForeignKeyConstraintName + '
GO'
FROM
@table
--ADD CONSTRAINT:
SELECT
'
ALTER TABLE [' + ForeignKeyConstraintTableSchema + '].[' + ForeignKeyConstraintTableName + ']
ADD CONSTRAINT ' + ForeignKeyConstraintName + ' FOREIGN KEY(' + ForeignKeyConstraintColumnName + ') REFERENCES [' + PrimaryKeyConstraintTableSchema + '].[' + PrimaryKeyConstraintTableName + '](' + PrimaryKeyConstraintColumnName + ')
GO'
FROM
@table
GO
我同意你的观点，哈姆林。当您使用SSIS传输数据或想要复制数据时，似乎很有必要暂时禁用或删除外键约束，然后重新启用或重新创建它们。在这些情况下，引用完整性不是问题，因为它已经在源数据库中进行了维护。所以，这件事你可以放心。
SET NOCOUNT ON
DECLARE @table TABLE(
RowId INT PRIMARY KEY IDENTITY(1, 1),
ForeignKeyConstraintName NVARCHAR(200),
ForeignKeyConstraintTableSchema NVARCHAR(200),
ForeignKeyConstraintTableName NVARCHAR(200),
ForeignKeyConstraintColumnName NVARCHAR(200),
PrimaryKeyConstraintName NVARCHAR(200),
PrimaryKeyConstraintTableSchema NVARCHAR(200),
PrimaryKeyConstraintTableName NVARCHAR(200),
PrimaryKeyConstraintColumnName NVARCHAR(200),
UpdateRule NVARCHAR(100),
DeleteRule NVARCHAR(100)
)
INSERT INTO @table(ForeignKeyConstraintName, ForeignKeyConstraintTableSchema, ForeignKeyConstraintTableName, ForeignKeyConstraintColumnName)
SELECT
U.CONSTRAINT_NAME,
U.TABLE_SCHEMA,
U.TABLE_NAME,
U.COLUMN_NAME
FROM
INFORMATION_SCHEMA.KEY_COLUMN_USAGE U
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS C
ON U.CONSTRAINT_NAME = C.CONSTRAINT_NAME
WHERE
C.CONSTRAINT_TYPE = 'FOREIGN KEY'
UPDATE @table SET
T.PrimaryKeyConstraintName = R.UNIQUE_CONSTRAINT_NAME,
T.UpdateRule = R.UPDATE_RULE,
T.DeleteRule = R.DELETE_RULE
FROM
@table T
INNER JOIN INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS R
ON T.ForeignKeyConstraintName = R.CONSTRAINT_NAME
UPDATE @table SET
PrimaryKeyConstraintTableSchema = TABLE_SCHEMA,
PrimaryKeyConstraintTableName = TABLE_NAME
FROM @table T
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS C
ON T.PrimaryKeyConstraintName = C.CONSTRAINT_NAME
UPDATE @table SET
PrimaryKeyConstraintColumnName = COLUMN_NAME
FROM @table T
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE U
ON T.PrimaryKeyConstraintName = U.CONSTRAINT_NAME
--SELECT * FROM @table
SELECT '
BEGIN TRANSACTION
BEGIN TRY'
--DROP CONSTRAINT:
SELECT
'
ALTER TABLE [' + ForeignKeyConstraintTableSchema + '].[' + ForeignKeyConstraintTableName + ']
DROP CONSTRAINT ' + ForeignKeyConstraintName + '
'
FROM
@table
SELECT '
END TRY
BEGIN CATCH
ROLLBACK TRANSACTION
RAISERROR(''Operation failed.'', 16, 1)
END CATCH
IF(@@TRANCOUNT != 0)
BEGIN
COMMIT TRANSACTION
RAISERROR(''Operation completed successfully.'', 10, 1)
END
'
--ADD CONSTRAINT:
SELECT '
BEGIN TRANSACTION
BEGIN TRY'
SELECT
'
ALTER TABLE [' + ForeignKeyConstraintTableSchema + '].[' + ForeignKeyConstraintTableName + ']
ADD CONSTRAINT ' + ForeignKeyConstraintName + ' FOREIGN KEY(' + ForeignKeyConstraintColumnName + ') REFERENCES [' + PrimaryKeyConstraintTableSchema + '].[' + PrimaryKeyConstraintTableName + '](' + PrimaryKeyConstraintColumnName + ') ON UPDATE ' + UpdateRule + ' ON DELETE ' + DeleteRule + '
'
FROM
@table
SELECT '
END TRY
BEGIN CATCH
ROLLBACK TRANSACTION
RAISERROR(''Operation failed.'', 16, 1)
END CATCH
IF(@@TRANCOUNT != 0)
BEGIN
COMMIT TRANSACTION
RAISERROR(''Operation completed successfully.'', 10, 1)
END'
GO
要禁用约束，您可以使用NOCHECK更改表
ALTER TABLE [TABLE_NAME] NOCHECK CONSTRAINT [ALL|CONSTRAINT_NAME]
要使您必须使用双重检查:
ALTER TABLE [TABLE_NAME] WITH CHECK CHECK CONSTRAINT [ALL|CONSTRAINT_NAME]
启用时请注意双重CHECK CHECK。 ALL表示表中的所有约束。
一旦完成，如果您需要检查状态，使用这个脚本列出约束状态。会很有帮助:
SELECT (CASE
WHEN OBJECTPROPERTY(CONSTID, 'CNSTISDISABLED') = 0 THEN 'ENABLED'
ELSE 'DISABLED'
END) AS STATUS,
OBJECT_NAME(CONSTID) AS CONSTRAINT_NAME,
OBJECT_NAME(FKEYID) AS TABLE_NAME,
COL_NAME(FKEYID, FKEY) AS COLUMN_NAME,
OBJECT_NAME(RKEYID) AS REFERENCED_TABLE_NAME,
COL_NAME(RKEYID, RKEY) AS REFERENCED_COLUMN_NAME
FROM SYSFOREIGNKEYS
ORDER BY TABLE_NAME, CONSTRAINT_NAME,REFERENCED_TABLE_NAME, KEYNO
最好的选择是DROP和CREATE外键约束。
我在这篇文章中没有找到对我“原样”工作的例子，如果外键引用不同的模式，一个不会工作，如果外键引用多列，另一个也不会工作。这个脚本同时考虑多个模式和每个外键的多个列。
下面是生成“ADD CONSTRAINT”语句的脚本，对于多列，它将用逗号分隔它们(确保在执行DROP语句之前保存此输出):
PRINT N'-- CREATE FOREIGN KEY CONSTRAINTS --';
SET NOCOUNT ON;
SELECT '
PRINT N''Creating '+ const.const_name +'...''
GO
ALTER TABLE ' + const.parent_obj + '
ADD CONSTRAINT ' + const.const_name + ' FOREIGN KEY (
' + const.parent_col_csv + '
) REFERENCES ' + const.ref_obj + '(' + const.ref_col_csv + ')
GO'
FROM (
SELECT QUOTENAME(fk.NAME) AS [const_name]
,QUOTENAME(schParent.NAME) + '.' + QUOTENAME(OBJECT_name(fkc.parent_object_id)) AS [parent_obj]
,STUFF((
SELECT ',' + QUOTENAME(COL_NAME(fcP.parent_object_id, fcp.parent_column_id))
FROM sys.foreign_key_columns AS fcP
WHERE fcp.constraint_object_id = fk.object_id
FOR XML path('')
), 1, 1, '') AS [parent_col_csv]
,QUOTENAME(schRef.NAME) + '.' + QUOTENAME(OBJECT_NAME(fkc.referenced_object_id)) AS [ref_obj]
,STUFF((
SELECT ',' + QUOTENAME(COL_NAME(fcR.referenced_object_id, fcR.referenced_column_id))
FROM sys.foreign_key_columns AS fcR
WHERE fcR.constraint_object_id = fk.object_id
FOR XML path('')
), 1, 1, '') AS [ref_col_csv]
FROM sys.foreign_key_columns AS fkc
INNER JOIN sys.foreign_keys AS fk ON fk.object_id = fkc.constraint_object_id
INNER JOIN sys.objects AS oParent ON oParent.object_id = fkc.parent_object_id
INNER JOIN sys.schemas AS schParent ON schParent.schema_id = oParent.schema_id
INNER JOIN sys.objects AS oRef ON oRef.object_id = fkc.referenced_object_id
INNER JOIN sys.schemas AS schRef ON schRef.schema_id = oRef.schema_id
GROUP BY fkc.parent_object_id
,fkc.referenced_object_id
,fk.NAME
,fk.object_id
,schParent.NAME
,schRef.NAME
) AS const
ORDER BY const.const_name
下面是生成“DROP CONSTRAINT”语句的脚本:
PRINT N'-- DROP FOREIGN KEY CONSTRAINTS --';
SET NOCOUNT ON;
SELECT '
PRINT N''Dropping ' + fk.NAME + '...''
GO
ALTER TABLE [' + sch.NAME + '].[' + OBJECT_NAME(fk.parent_object_id) + ']' + ' DROP CONSTRAINT ' + '[' + fk.NAME + ']
GO'
FROM sys.foreign_keys AS fk
INNER JOIN sys.schemas AS sch ON sch.schema_id = fk.schema_id
ORDER BY fk.NAME
找到约束条件
SELECT *
FROM sys.foreign_keys
WHERE referenced_object_id = object_id('TABLE_NAME')
执行由此SQL生成的SQL
SELECT
'ALTER TABLE ' + OBJECT_SCHEMA_NAME(parent_object_id) +
'.[' + OBJECT_NAME(parent_object_id) +
'] DROP CONSTRAINT ' + name
FROM sys.foreign_keys
WHERE referenced_object_id = object_id('TABLE_NAME')
西夫韦。
注意:增加了删除约束的解决方案，这样可以删除或修改表而没有任何约束错误。
第一篇文章:)
对于OP, kristof的解决方案是有效的，除非在大删除上存在大量数据和事务日志气球问题。此外，即使有空闲的tlog存储空间，由于删除写入tlog，对于具有数亿行的表，操作可能会花费非常长的时间。
我经常使用一系列游标来截断和重新加载我们的大型生产数据库之一的大型副本。设计的解决方案支持多个模式、多个外键列，最重要的是可以在SSIS中使用。
It involves creation of three staging tables (real tables) to house the DROP, CREATE, and CHECK FK scripts, creation and insertion of those scripts into the tables, and then looping over the tables and executing them. The attached script is four parts: 1.) creation and storage of the scripts in the three staging (real) tables, 2.) execution of the drop FK scripts via a cursor one by one, 3.) Using sp_MSforeachtable to truncate all the tables in the database other than our three staging tables and 4.) execution of the create FK and check FK scripts at the end of your ETL SSIS package.
在SSIS中的Execute SQL任务中运行脚本创建部分。在第二个执行SQL任务中运行“execute Drop FK Scripts”部分。将截断脚本放在第三个Execute SQL任务中，然后在控制流末尾的最后一个Execute SQL任务(如果需要的话可以是两个)中附加CREATE和CHECK脚本之前，执行您需要执行的任何其他ETL过程。
当重新应用外键失败时，在实际表中存储脚本被证明是非常宝贵的，因为您可以从sync_CreateFK中选择*，复制/粘贴到查询窗口中，一次运行一个，并在发现失败/仍然无法重新应用的数据时修复数据问题。
如果脚本失败，请不要再次重新运行脚本，否则您很可能会丢失一些创建和检查fk脚本，因为在创建要执行的脚本之前，我们的staging表会被删除并重新创建。
----------------------------------------------------------------------------
1)
/*
Author: Denmach
DateCreated: 2014-04-23
Purpose: Generates SQL statements to DROP, ADD, and CHECK existing constraints for a
database. Stores scripts in tables on target database for execution. Executes
those stored scripts via independent cursors.
DateModified:
ModifiedBy
Comments: This will eliminate deletes and the T-log ballooning associated with it.
*/
DECLARE @schema_name SYSNAME;
DECLARE @table_name SYSNAME;
DECLARE @constraint_name SYSNAME;
DECLARE @constraint_object_id INT;
DECLARE @referenced_object_name SYSNAME;
DECLARE @is_disabled BIT;
DECLARE @is_not_for_replication BIT;
DECLARE @is_not_trusted BIT;
DECLARE @delete_referential_action TINYINT;
DECLARE @update_referential_action TINYINT;
DECLARE @tsql NVARCHAR(4000);
DECLARE @tsql2 NVARCHAR(4000);
DECLARE @fkCol SYSNAME;
DECLARE @pkCol SYSNAME;
DECLARE @col1 BIT;
DECLARE @action CHAR(6);
DECLARE @referenced_schema_name SYSNAME;
--------------------------------Generate scripts to drop all foreign keys in a database --------------------------------
IF OBJECT_ID('dbo.sync_dropFK') IS NOT NULL
DROP TABLE sync_dropFK
CREATE TABLE sync_dropFK
(
ID INT IDENTITY (1,1) NOT NULL
, Script NVARCHAR(4000)
)
DECLARE FKcursor CURSOR FOR
SELECT
OBJECT_SCHEMA_NAME(parent_object_id)
, OBJECT_NAME(parent_object_id)
, name
FROM
sys.foreign_keys WITH (NOLOCK)
ORDER BY
1,2;
OPEN FKcursor;
FETCH NEXT FROM FKcursor INTO
@schema_name
, @table_name
, @constraint_name
WHILE @@FETCH_STATUS = 0
BEGIN
SET @tsql = 'ALTER TABLE '
+ QUOTENAME(@schema_name)
+ '.'
+ QUOTENAME(@table_name)
+ ' DROP CONSTRAINT '
+ QUOTENAME(@constraint_name)
+ ';';
--PRINT @tsql;
INSERT sync_dropFK (
Script
)
VALUES (
@tsql
)
FETCH NEXT FROM FKcursor INTO
@schema_name
, @table_name
, @constraint_name
;
END;
CLOSE FKcursor;
DEALLOCATE FKcursor;
---------------Generate scripts to create all existing foreign keys in a database --------------------------------
----------------------------------------------------------------------------------------------------------
IF OBJECT_ID('dbo.sync_createFK') IS NOT NULL
DROP TABLE sync_createFK
CREATE TABLE sync_createFK
(
ID INT IDENTITY (1,1) NOT NULL
, Script NVARCHAR(4000)
)
IF OBJECT_ID('dbo.sync_createCHECK') IS NOT NULL
DROP TABLE sync_createCHECK
CREATE TABLE sync_createCHECK
(
ID INT IDENTITY (1,1) NOT NULL
, Script NVARCHAR(4000)
)
DECLARE FKcursor CURSOR FOR
SELECT
OBJECT_SCHEMA_NAME(parent_object_id)
, OBJECT_NAME(parent_object_id)
, name
, OBJECT_NAME(referenced_object_id)
, OBJECT_ID
, is_disabled
, is_not_for_replication
, is_not_trusted
, delete_referential_action
, update_referential_action
, OBJECT_SCHEMA_NAME(referenced_object_id)
FROM
sys.foreign_keys WITH (NOLOCK)
ORDER BY
1,2;
OPEN FKcursor;
FETCH NEXT FROM FKcursor INTO
@schema_name
, @table_name
, @constraint_name
, @referenced_object_name
, @constraint_object_id
, @is_disabled
, @is_not_for_replication
, @is_not_trusted
, @delete_referential_action
, @update_referential_action
, @referenced_schema_name;
WHILE @@FETCH_STATUS = 0
BEGIN
BEGIN
SET @tsql = 'ALTER TABLE '
+ QUOTENAME(@schema_name)
+ '.'
+ QUOTENAME(@table_name)
+ CASE
@is_not_trusted
WHEN 0 THEN ' WITH CHECK '
ELSE ' WITH NOCHECK '
END
+ ' ADD CONSTRAINT '
+ QUOTENAME(@constraint_name)
+ ' FOREIGN KEY (';
SET @tsql2 = '';
DECLARE ColumnCursor CURSOR FOR
SELECT
COL_NAME(fk.parent_object_id
, fkc.parent_column_id)
, COL_NAME(fk.referenced_object_id
, fkc.referenced_column_id)
FROM
sys.foreign_keys fk WITH (NOLOCK)
INNER JOIN sys.foreign_key_columns fkc WITH (NOLOCK) ON fk.[object_id] = fkc.constraint_object_id
WHERE
fkc.constraint_object_id = @constraint_object_id
ORDER BY
fkc.constraint_column_id;
OPEN ColumnCursor;
SET @col1 = 1;
FETCH NEXT FROM ColumnCursor INTO @fkCol, @pkCol;
WHILE @@FETCH_STATUS = 0
BEGIN
IF (@col1 = 1)
SET @col1 = 0;
ELSE
BEGIN
SET @tsql = @tsql + ',';
SET @tsql2 = @tsql2 + ',';
END;
SET @tsql = @tsql + QUOTENAME(@fkCol);
SET @tsql2 = @tsql2 + QUOTENAME(@pkCol);
--PRINT '@tsql = ' + @tsql
--PRINT '@tsql2 = ' + @tsql2
FETCH NEXT FROM ColumnCursor INTO @fkCol, @pkCol;
--PRINT 'FK Column ' + @fkCol
--PRINT 'PK Column ' + @pkCol
END;
CLOSE ColumnCursor;
DEALLOCATE ColumnCursor;
SET @tsql = @tsql + ' ) REFERENCES '
+ QUOTENAME(@referenced_schema_name)
+ '.'
+ QUOTENAME(@referenced_object_name)
+ ' ('
+ @tsql2 + ')';
SET @tsql = @tsql
+ ' ON UPDATE '
+
CASE @update_referential_action
WHEN 0 THEN 'NO ACTION '
WHEN 1 THEN 'CASCADE '
WHEN 2 THEN 'SET NULL '
ELSE 'SET DEFAULT '
END
+ ' ON DELETE '
+
CASE @delete_referential_action
WHEN 0 THEN 'NO ACTION '
WHEN 1 THEN 'CASCADE '
WHEN 2 THEN 'SET NULL '
ELSE 'SET DEFAULT '
END
+
CASE @is_not_for_replication
WHEN 1 THEN ' NOT FOR REPLICATION '
ELSE ''
END
+ ';';
END;
-- PRINT @tsql
INSERT sync_createFK
(
Script
)
VALUES (
@tsql
)
-------------------Generate CHECK CONSTRAINT scripts for a database ------------------------------
----------------------------------------------------------------------------------------------------------
BEGIN
SET @tsql = 'ALTER TABLE '
+ QUOTENAME(@schema_name)
+ '.'
+ QUOTENAME(@table_name)
+
CASE @is_disabled
WHEN 0 THEN ' CHECK '
ELSE ' NOCHECK '
END
+ 'CONSTRAINT '
+ QUOTENAME(@constraint_name)
+ ';';
--PRINT @tsql;
INSERT sync_createCHECK
(
Script
)
VALUES (
@tsql
)
END;
FETCH NEXT FROM FKcursor INTO
@schema_name
, @table_name
, @constraint_name
, @referenced_object_name
, @constraint_object_id
, @is_disabled
, @is_not_for_replication
, @is_not_trusted
, @delete_referential_action
, @update_referential_action
, @referenced_schema_name;
END;
CLOSE FKcursor;
DEALLOCATE FKcursor;
--SELECT * FROM sync_DropFK
--SELECT * FROM sync_CreateFK
--SELECT * FROM sync_CreateCHECK
---------------------------------------------------------------------------
2.)
-----------------------------------------------------------------------------------------------------------------
----------------------------execute Drop FK Scripts --------------------------------------------------
DECLARE @scriptD NVARCHAR(4000)
DECLARE DropFKCursor CURSOR FOR
SELECT Script
FROM sync_dropFK WITH (NOLOCK)
OPEN DropFKCursor
FETCH NEXT FROM DropFKCursor
INTO @scriptD
WHILE @@FETCH_STATUS = 0
BEGIN
--PRINT @scriptD
EXEC (@scriptD)
FETCH NEXT FROM DropFKCursor
INTO @scriptD
END
CLOSE DropFKCursor
DEALLOCATE DropFKCursor
--------------------------------------------------------------------------------
3.)
------------------------------------------------------------------------------------------------------------------
----------------------------Truncate all tables in the database other than our staging tables --------------------
------------------------------------------------------------------------------------------------------------------
EXEC sp_MSforeachtable 'IF OBJECT_ID(''?'') NOT IN
(
ISNULL(OBJECT_ID(''dbo.sync_createCHECK''),0),
ISNULL(OBJECT_ID(''dbo.sync_createFK''),0),
ISNULL(OBJECT_ID(''dbo.sync_dropFK''),0)
)
BEGIN TRY
TRUNCATE TABLE ?
END TRY
BEGIN CATCH
PRINT ''Truncation failed on''+ ? +''
END CATCH;'
GO
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------
----------------------------execute Create FK Scripts and CHECK CONSTRAINT Scripts---------------
----------------------------tack me at the end of the ETL in a SQL task-------------------------
-------------------------------------------------------------------------------------------------
DECLARE @scriptC NVARCHAR(4000)
DECLARE CreateFKCursor CURSOR FOR
SELECT Script
FROM sync_createFK WITH (NOLOCK)
OPEN CreateFKCursor
FETCH NEXT FROM CreateFKCursor
INTO @scriptC
WHILE @@FETCH_STATUS = 0
BEGIN
--PRINT @scriptC
EXEC (@scriptC)
FETCH NEXT FROM CreateFKCursor
INTO @scriptC
END
CLOSE CreateFKCursor
DEALLOCATE CreateFKCursor
-------------------------------------------------------------------------------------------------
DECLARE @scriptCh NVARCHAR(4000)
DECLARE CreateCHECKCursor CURSOR FOR
SELECT Script
FROM sync_createCHECK WITH (NOLOCK)
OPEN CreateCHECKCursor
FETCH NEXT FROM CreateCHECKCursor
INTO @scriptCh
WHILE @@FETCH_STATUS = 0
BEGIN
--PRINT @scriptCh
EXEC (@scriptCh)
FETCH NEXT FROM CreateCHECKCursor
INTO @scriptCh
END
CLOSE CreateCHECKCursor
DEALLOCATE CreateCHECKCursor
几乎可以肯定，检查是必须的!
在一些回答和评论中提出了这一点，但我认为再次提出这一点非常重要。
使用以下命令(不使用WITH CHECK)重新启用约束会有一些严重的缺陷。
ALTER TABLE MyTable CHECK CONSTRAINT MyConstraint;
WITH CHECK | WITH NOCHECK Specifies whether the data in the table is or is not validated against a newly added or re-enabled FOREIGN KEY or CHECK constraint. If not specified, WITH CHECK is assumed for new constraints, and WITH NOCHECK is assumed for re-enabled constraints. If you do not want to verify new CHECK or FOREIGN KEY constraints against existing data, use WITH NOCHECK. We do not recommend doing this, except in rare cases. The new constraint will be evaluated in all later data updates. Any constraint violations that are suppressed by WITH NOCHECK when the constraint is added may cause future updates to fail if they update rows with data that does not comply with the constraint. The query optimizer does not consider constraints that are defined WITH NOCHECK. Such constraints are ignored until they are re-enabled by using ALTER TABLE table WITH CHECK CHECK CONSTRAINT ALL.
注意:WITH NOCHECK是重新启用约束的默认值。我想知道为什么……
No existing data in the table will be evaluated during the execution of this command - successful completion is no guarantee that the data in the table is valid according to the constraint. During the next update of the invalid records, the constraint will be evaluated and will fail - resulting in errors that may be unrelated to the actual update that is made. Application logic that relies on the constraint to ensure that data is valid may fail. The query optimizer will not make use of any constraint that is enabled in this way.
sys。Foreign_keys系统视图提供了一些问题的可见性。注意，它有一个is_disabled列和一个is_not_trusted列。Is_disabled指示是否根据约束验证未来的数据操作。Is_not_trusted指示表中当前的所有数据是否已经根据约束进行了验证。
ALTER TABLE MyTable WITH CHECK CHECK CONSTRAINT MyConstraint;
你的约束是可信的吗?找出……
SELECT * FROM sys.foreign_keys WHERE is_not_trusted = 1;
如果你感兴趣，我有一个更有用的版本。我从这里提取了一些代码，一个网站的链接不再活跃。我修改了它，以允许存储过程中有一个表数组，并在执行所有语句之前填充删除、截断和添加语句。这使您可以控制决定哪些表需要截断。
/****** Object: UserDefinedTableType [util].[typ_objects_for_managing] Script Date: 03/04/2016 16:42:55 ******/
CREATE TYPE [util].[typ_objects_for_managing] AS TABLE(
[schema] [sysname] NOT NULL,
[object] [sysname] NOT NULL
)
GO
create procedure [util].[truncate_table_with_constraints]
@objects_for_managing util.typ_objects_for_managing readonly
--@schema sysname
--,@table sysname
as
--select
-- @table = 'TABLE',
-- @schema = 'SCHEMA'
declare @exec_table as table (ordinal int identity (1,1), statement nvarchar(4000), primary key (ordinal));
--print '/*Drop Foreign Key Statements for ['+@schema+'].['+@table+']*/'
insert into @exec_table (statement)
select
'ALTER TABLE ['+SCHEMA_NAME(o.schema_id)+'].['+ o.name+'] DROP CONSTRAINT ['+fk.name+']'
from sys.foreign_keys fk
inner join sys.objects o
on fk.parent_object_id = o.object_id
where
exists (
select * from @objects_for_managing chk
where
chk.[schema] = SCHEMA_NAME(o.schema_id)
and
chk.[object] = o.name
)
;
--o.name = @table and
--SCHEMA_NAME(o.schema_id) = @schema
insert into @exec_table (statement)
select
'TRUNCATE TABLE ' + src.[schema] + '.' + src.[object]
from @objects_for_managing src
;
--print '/*Create Foreign Key Statements for ['+@schema+'].['+@table+']*/'
insert into @exec_table (statement)
select 'ALTER TABLE ['+SCHEMA_NAME(o.schema_id)+'].['+o.name+'] ADD CONSTRAINT ['+fk.name+'] FOREIGN KEY (['+c.name+'])
REFERENCES ['+SCHEMA_NAME(refob.schema_id)+'].['+refob.name+'](['+refcol.name+'])'
from sys.foreign_key_columns fkc
inner join sys.foreign_keys fk
on fkc.constraint_object_id = fk.object_id
inner join sys.objects o
on fk.parent_object_id = o.object_id
inner join sys.columns c
on fkc.parent_column_id = c.column_id and
o.object_id = c.object_id
inner join sys.objects refob
on fkc.referenced_object_id = refob.object_id
inner join sys.columns refcol
on fkc.referenced_column_id = refcol.column_id and
fkc.referenced_object_id = refcol.object_id
where
exists (
select * from @objects_for_managing chk
where
chk.[schema] = SCHEMA_NAME(o.schema_id)
and
chk.[object] = o.name
)
;
--o.name = @table and
--SCHEMA_NAME(o.schema_id) = @schema
declare @looper int , @total_records int, @sql_exec nvarchar(4000)
select @looper = 1, @total_records = count(*) from @exec_table;
while @looper <= @total_records
begin
select @sql_exec = (select statement from @exec_table where ordinal =@looper)
exec sp_executesql @sql_exec
print @sql_exec
set @looper = @looper + 1
end
一个脚本来管理它们:这个脚本将截断和删除命令与sp_MSforeachtable结合在一起，这样您就可以避免删除和重新创建约束——只需指定需要删除而不是截断的表，为了便于度量，我还包含了一个额外的模式过滤器(在2008r2中测试)。
declare @schema nvarchar(max) = 'and Schema_Id=Schema_id(''Value'')'
declare @deletiontables nvarchar(max) = '(''TableA'',''TableB'')'
declare @truncateclause nvarchar(max) = @schema + ' and o.Name not in ' + + @deletiontables;
declare @deleteclause nvarchar(max) = @schema + ' and o.Name in ' + @deletiontables;
exec sp_MSforeachtable 'alter table ? nocheck constraint all', @whereand=@schema
exec sp_MSforeachtable 'truncate table ?', @whereand=@truncateclause
exec sp_MSforeachtable 'delete from ?', @whereand=@deleteclause
exec sp_MSforeachtable 'alter table ? with check check constraint all', @whereand=@schema
标记为“905”的答案看起来不错，但不能工作。
下面的方法对我很有效。不能禁用任何主键、唯一键或默认约束。事实上，如果“sp_helpconstraint”在status_enabled中显示“n/a”-意味着它不能被启用/禁用。
生成脚本为DISABLE
select 'ALTER TABLE ' + object_name(id) + ' NOCHECK CONSTRAINT [' + object_name(constid) + ']'
from sys.sysconstraints
where status & 0x4813 = 0x813 order by object_name(id)
——生成脚本以启用
select 'ALTER TABLE ' + object_name(id) + ' CHECK CONSTRAINT [' + object_name(constid) + ']'
from sys.sysconstraints
where status & 0x4813 = 0x813 order by object_name(id)
实际上，你应该能够像暂时禁用其他约束一样禁用外键约束:
Alter table MyTable nocheck constraint FK_ForeignKeyConstraintName
只需确保在约束名称中列出的第一个表上禁用了约束。例如，如果我的外键约束是FK_LocationsEmployeesLocationIdEmployeeId，我想使用以下:
Alter table Locations nocheck constraint FK_LocationsEmployeesLocationIdEmployeeId
尽管违反这个约束会产生一个错误，这个错误不一定会将该表作为冲突的来源。
您可以暂时禁用表上的约束，进行工作，然后重新构建它们。
这里有一个简单的方法…
禁用所有索引，包括主键，这将禁用所有外键，然后重新启用主键，以便您可以使用它们…
DECLARE @sql AS NVARCHAR(max)=''
select @sql = @sql +
'ALTER INDEX ALL ON [' + t.[name] + '] DISABLE;'+CHAR(13)
from
sys.tables t
where type='u'
select @sql = @sql +
'ALTER INDEX ' + i.[name] + ' ON [' + t.[name] + '] REBUILD;'+CHAR(13)
from
sys.key_constraints i
join
sys.tables t on i.parent_object_id=t.object_id
where
i.type='PK'
exec dbo.sp_executesql @sql;
go
[做一些事情，比如加载数据]
然后重新启用和重建索引……
DECLARE @sql AS NVARCHAR(max)=''
select @sql = @sql +
'ALTER INDEX ALL ON [' + t.[name] + '] REBUILD;'+CHAR(13)
from
sys.tables t
where type='u'
exec dbo.sp_executesql @sql;
go
推荐文章
- 我如何在T-SQL用逗号格式化一个数字?
- LEFT OUTER JOIN如何返回比左表中存在的记录更多的记录?
- 如何用SQL语句计算百分比
- SQL Server动态PIVOT查询?
- 如何等待2秒?
- SQL Server: CROSS JOIN和FULL OUTER JOIN的区别是什么?
- varchar和nvarchar SQL Server数据类型之间的主要性能差异是什么?
- 向现有表添加主键
- Mysql错误1452:不能添加或更新子行:外键约束失败
- 错误:没有唯一的约束匹配给定的键引用表"bar"
- 我应该在SQL varchar(长度)中考虑电话的最长的全球电话号码是什么
- T-SQL CASE子句:如何指定WHEN NULL
- 表中标识列的显式值只能在使用列列表且IDENTITY_INSERT为ON SQL Server时指定
- 如何确定已安装的SQL Server实例及其版本?
- Scope_Identity()、Identity()、@@Identity和Ident_Current()之间的区别是什么?
