外键开关
2024-07-21 02:08:05
供稿：网友
最近在做假资料时经常需要删除一些表中的内容。但是：
设置外键后，想删除表中的数据无法删除，这时需删除外键后重建，
或找到外键后用 alter table 表名 nocheck 外键名 来暂时屏蔽外键，然后删除。
干脆写个存储过程，设置外键的开关。
exec fk_switch '表名',0 屏蔽外键
exec fk_switch '表名',1 重启外键
/* usage:
exec fk_switch 'tablename',0
delete tablename where fieldname = 'abc'
-- truncate table tablename
exec fk_switch 'tablename',1
*/
create proc fk_switch @tablename varchar(20),@status bit
as
declare @fk varchar(50),@fktable varchar(20)
declare @s varchar(1000)
declare cur cursor for
select b.name as fkname,c.name as fktablename
from sysforeignkeys a
join sysobjects b on a.constid = b.id
join sysobjects c on a.fkeyid = c.id
join sysobjects d on a.rkeyid = d.id
where d.name = @tablename
open cur
fetch next from cur into @fk,@fktable
while @@fetch_status = 0
begin
if @status = 0
begin
set @s = 'alter table '[email protected]+' nocheck constraint '+ @fk
print @s
end
else
begin
set @s = 'alter table '[email protected]+' check constraint '+ @fk
print @s
end
exec(@s)
fetch next from cur into @fk,@fktable
end
close cur
deallocate cur
go
--以下为测试：
create table a (id int primary key)
go
create table b(id int,
constraint fk_b_a foreign key (id) references a (id))
go
create table c(id int,
constraint fk_c_a foreign key (id) references a (id))
go
insert a values (1)
insert b values(1)
insert c values (1)
--1:
delete a
/*****
服务器: 消息 547，级别 16，状态 1，行 1
delete statement conflicted with column reference constraint 'fk_b_a'. the conflict occurred in database 'pubs', table 'b', column 'id'.
the statement has been terminated.
*******/
--2:
begin tran
exec fk_switch 'a',0
delete a
exec fk_switch 'a',1
rollback
/*
alter table b nocheck constraint fk_b_a
alter table c nocheck constraint fk_c_a
（所影响的行数为 1 行）
alter table b check constraint fk_b_a
alter table c check constraint fk_c_a
*/
--3: 清除测试表
drop table a,b,c
go
