教你快速掌握SQL Server锁的相关概念

设table1(A,B,C) 
A B C 
a1 b1 c1 
a2 b2 c2 
a3 b3 c3

begin tran 
update table1 
set A='aa' 
where B='b2' 
waitfor delay '00:00:30' --等待30秒 
commit tran 
在第二个连接中执行以下语句 
begin tran 
select * from table1 
where B='b2' 
commit tran

begin tran 
select * from table1 holdlock -holdlock人为加锁 
where B='b2' 
waitfor delay '00:00:30' --等待30秒 
commit tran

begin tran 
select * from table1 holdlock -holdlock人为加锁 
where B='b2' 
waitfor delay '00:00:30' --等待30秒 
commit tran

begin tran 
select A,C from table1 
where B='b2' 
update table1 
set A='aa' 
where B='b2' 
commit tran