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
如果这些答案都不像我的情况那样有效,那就这样做:
减少约束 将所有值设置为允许为空 截断表 添加已删除的约束。
好运!
其他回答
我刚刚发现,只要先禁用子表上的外键约束,就可以在父表上使用TRUNCATE表。 如。
子表上的外键约束child_par_ref引用PARENT_TABLE
ALTER TABLE CHILD_TABLE DISABLE CONSTRAINT child_par_ref;
TRUNCATE TABLE CHILD_TABLE;
TRUNCATE TABLE PARENT_TABLE;
ALTER TABLE CHILD_TABLE ENABLE CONSTRAINT child_par_ref;
最简单的方法: 1 -在phpmyadmin中输入 2 -点击左列的表名 3 -点击操作(顶部菜单) 4 -点击“清空表格(TRUNCATE)” 5 -禁用框“启用外键检查” 6 -完成!
图片教程链接 教程:http://www.imageno.com/wz6gv1wuqajrpic.html (对不起,我没有足够的声誉上传图片:P)
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'
如果这些答案都不像我的情况那样有效,那就这样做:
减少约束 将所有值设置为允许为空 截断表 添加已删除的约束。
好运!
DELETE FROM TABLENAME
DBCC CHECKIDENT ('DATABASENAME.dbo.TABLENAME', RESEED, 0)
注意,如果您有数百万条以上的记录,这可能不是您想要的,因为它非常慢。