sql不常用函数总结以及事务，增加，删除触发器

答案：sql不常用函数总结以及事务，增加，删除触发器 

distinct 删除重复行 

declare @x 申明一个变量 

convert(varchar(20),tscore.tenglish) 类型转换 

cast(xx as varchar(10)) 类型转换 
www.zzzyk.com 
====================================================== 

情况 
case 
when xxx then xx 
when xxxx then xxxxx 
else 
end 

======================================================= 

while xxx 
begin 
xxxxxx 
end 
www.zzzyk.com 
事务 
=================================================== 
begin tran 
declare @sum int = 0 
update bank set balance=balance-1000 where cid='0001' 
set @sum=@sum+@@error 
update bank set balance=balance + 1000 where cid='0002' 
set @sum=@sum+@@error 

if @sum<>0 
begin 
rollback 
print '回滚！' 
end 
else 
begin 
--提交事务 
commit tran 
print '提交了！' 
end 
=================================================== 
begin tran www.zzzyk.com 
begin try 
declare @sum int = 0 
update bank set balance=balance-900 where cid='0001' 
set @sum=@sum+@@error 
update bank set balance=balance + 900 where cid='0002' 
set @sum=@sum+@@error 
commit 
end try 
begin catch 
rollback 
end catch 
===================================================== 

declare @halfCount int= ceiling(@count/2.0) 向上 

增加时触发器 
========================================= 
create trigger tri_TblClass_insert_after 
on TblClass after insert 
as 
begin 
declare @id int 
declare @name varchar(50) 
declare @desc varchar(50) 
select @id=tclassId,@name=tclassname,@desc=tclassdesc from inserted 

print @id 
print @name 
print @desc 
end www.zzzyk.com 
========================================= 

删除时触发器 
create trigger tri_TblClass_delete_after 
on TblClass instead of delete 
as 
begin 

insert into TblClassBak 
select * from deleted 
end 
======================================== 


作者 xhccom

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