使用MSSQL2005,如果我首先截断子表(具有FK关系的主键的表),我可以截断带有外键约束的表吗?
我知道我也可以
使用不带where子句的DELETE,然后RESEED标识(或) 删除FK,截断表,并重新创建FK。
我认为只要我在父表之前截断子表,我就可以不做上面的任何一个选项,但我得到了这个错误:
不能截断表'TableName',因为它被一个FOREIGN KEY约束引用。
使用MSSQL2005,如果我首先截断子表(具有FK关系的主键的表),我可以截断带有外键约束的表吗?
我知道我也可以
使用不带where子句的DELETE,然后RESEED标识(或) 删除FK,截断表,并重新创建FK。
我认为只要我在父表之前截断子表,我就可以不做上面的任何一个选项,但我得到了这个错误:
不能截断表'TableName',因为它被一个FOREIGN KEY约束引用。
当前回答
这是我对这个问题的解决方案。我用它来改变PK,但想法是一样的。希望这将是有用的)
PRINT 'Script starts'
DECLARE @foreign_key_name varchar(255)
DECLARE @keycnt int
DECLARE @foreign_table varchar(255)
DECLARE @foreign_column_1 varchar(255)
DECLARE @foreign_column_2 varchar(255)
DECLARE @primary_table varchar(255)
DECLARE @primary_column_1 varchar(255)
DECLARE @primary_column_2 varchar(255)
DECLARE @TablN varchar(255)
-->> Type the primary table name
SET @TablN = ''
--------------------------------------------------------------------------------------- ------------------------------
--Here will be created the temporary table with all reference FKs
---------------------------------------------------------------------------------------------------------------------
PRINT 'Creating the temporary table'
select cast(f.name as varchar(255)) as foreign_key_name
, r.keycnt
, cast(c.name as varchar(255)) as foreign_table
, cast(fc.name as varchar(255)) as foreign_column_1
, cast(fc2.name as varchar(255)) as foreign_column_2
, cast(p.name as varchar(255)) as primary_table
, cast(rc.name as varchar(255)) as primary_column_1
, cast(rc2.name as varchar(255)) as primary_column_2
into #ConTab
from sysobjects f
inner join sysobjects c on f.parent_obj = c.id
inner join sysreferences r on f.id = r.constid
inner join sysobjects p on r.rkeyid = p.id
inner join syscolumns rc on r.rkeyid = rc.id and r.rkey1 = rc.colid
inner join syscolumns fc on r.fkeyid = fc.id and r.fkey1 = fc.colid
left join syscolumns rc2 on r.rkeyid = rc2.id and r.rkey2 = rc.colid
left join syscolumns fc2 on r.fkeyid = fc2.id and r.fkey2 = fc.colid
where f.type = 'F' and p.name = @TablN
ORDER BY cast(p.name as varchar(255))
---------------------------------------------------------------------------------------------------------------------
--Cursor, below, will drop all reference FKs
---------------------------------------------------------------------------------------------------------------------
DECLARE @CURSOR CURSOR
/*Fill in cursor*/
PRINT 'Cursor 1 starting. All refernce FK will be droped'
SET @CURSOR = CURSOR SCROLL
FOR
select foreign_key_name
, keycnt
, foreign_table
, foreign_column_1
, foreign_column_2
, primary_table
, primary_column_1
, primary_column_2
from #ConTab
OPEN @CURSOR
FETCH NEXT FROM @CURSOR INTO @foreign_key_name, @keycnt, @foreign_table, @foreign_column_1, @foreign_column_2,
@primary_table, @primary_column_1, @primary_column_2
WHILE @@FETCH_STATUS = 0
BEGIN
EXEC ('ALTER TABLE ['+@foreign_table+'] DROP CONSTRAINT ['+@foreign_key_name+']')
FETCH NEXT FROM @CURSOR INTO @foreign_key_name, @keycnt, @foreign_table, @foreign_column_1, @foreign_column_2,
@primary_table, @primary_column_1, @primary_column_2
END
CLOSE @CURSOR
PRINT 'Cursor 1 finished work'
---------------------------------------------------------------------------------------------------------------------
--Here you should provide the chainging script for the primary table
---------------------------------------------------------------------------------------------------------------------
PRINT 'Altering primary table begin'
TRUNCATE TABLE table_name
PRINT 'Altering finished'
---------------------------------------------------------------------------------------------------------------------
--Cursor, below, will add again all reference FKs
--------------------------------------------------------------------------------------------------------------------
PRINT 'Cursor 2 starting. All refernce FK will added'
SET @CURSOR = CURSOR SCROLL
FOR
select foreign_key_name
, keycnt
, foreign_table
, foreign_column_1
, foreign_column_2
, primary_table
, primary_column_1
, primary_column_2
from #ConTab
OPEN @CURSOR
FETCH NEXT FROM @CURSOR INTO @foreign_key_name, @keycnt, @foreign_table, @foreign_column_1, @foreign_column_2,
@primary_table, @primary_column_1, @primary_column_2
WHILE @@FETCH_STATUS = 0
BEGIN
EXEC ('ALTER TABLE [' +@foreign_table+ '] WITH NOCHECK ADD CONSTRAINT [' +@foreign_key_name+ '] FOREIGN KEY(['+@foreign_column_1+'])
REFERENCES [' +@primary_table+'] (['+@primary_column_1+'])')
EXEC ('ALTER TABLE [' +@foreign_table+ '] CHECK CONSTRAINT [' +@foreign_key_name+']')
FETCH NEXT FROM @CURSOR INTO @foreign_key_name, @keycnt, @foreign_table, @foreign_column_1, @foreign_column_2,
@primary_table, @primary_column_1, @primary_column_2
END
CLOSE @CURSOR
PRINT 'Cursor 2 finished work'
---------------------------------------------------------------------------------------------------------------------
PRINT 'Temporary table droping'
drop table #ConTab
PRINT 'Finish'
其他回答
截断不适合我,删除+重新播种是最好的方法。 如果你们中的一些人需要遍历大量的表来执行delete + reseed,你可能会遇到一些没有标识列的表的问题,下面的代码在尝试重新播种之前检查标识列是否存在
EXEC ('DELETE FROM [schemaName].[tableName]')
IF EXISTS (Select * from sys.identity_columns where object_name(object_id) = 'tableName')
BEGIN
EXEC ('DBCC CHECKIDENT ([schemaName.tableName], RESEED, 0)')
END
SET FOREIGN_KEY_CHECKS=0;
TRUNCATE table1;
TRUNCATE table2;
SET FOREIGN_KEY_CHECKS=1;
引用-截断外键约束表
在MYSQL为我工作
因为TRUNCATE TABLE是一个DDL命令,所以它不能检查表中的记录是否被子表中的记录引用。
这就是为什么DELETE有效而TRUNCATE TABLE无效的原因:因为数据库能够确保它没有被另一条记录引用。
对于MS SQL,至少在更新的版本中,你可以通过如下代码禁用约束:
ALTER TABLE Orders
NOCHECK CONSTRAINT [FK_dbo.Orders_dbo.Customers_Customer_Id]
GO
TRUNCATE TABLE Customers
GO
ALTER TABLE Orders
WITH CHECK CHECK CONSTRAINT [FK_dbo.Orders_dbo.Customers_Customer_Id]
GO
这是一个使用实体框架的人的例子
要重置的表:Foo 另一个表取决于:酒吧 约束表Foo上的列:FooColumn 表Bar上的约束列:BarColumn 公共覆盖无效Down() { DropForeignKey(“dbo。Bar", "BarColumn", "dbo.Foo"); Sql("TRUNCATE TABLE Foo"); AddForeignKey(“dbo。Bar", "BarColumn", "dbo "。Foo", "FooColumn", cascadeDelete: true); }