Question

我想在sql中选择一条记录，然后在一个语句或存储过程中更新它。

所以，我有这样的陈述：

select top 1 ID, TimeStamp, Locked, Deleted 
from TableName 
where Locked='False' and Deleted='False' 
order by TimeStamp asc

如何选择该语句，然后设置Locked =＆＃39; True＆＃39;返回记录。

Answer 1

如果您使用输出子句，则可以通过选择deleted

来查看更新后的更新记录。

with cte as (
    select  top 1 
            ID, 
            TimeStamp, 
            Locked, 
            Deleted 
    from    TableName 
    where   Locked='False' and Deleted='False' 
    order by TimeStamp asc
)
update  cte 
set     Locked = 'True'
output  deleted.*

Answer 2

如果您需要锁定，那么我认为这样做会问题是您无法将top与update一起使用。

create table #T (pk int identity primary key, ts timestamp not null, lock bit not null)
insert into #T (lock) values (1), (0), (1), (0), (0);
select * 
from #T t
order by t.ts asc;

update tt 
set tt.lock = 1 
output deleted.*
from ( select top(1) t.* 
       from #T t with (UPDLOCK ROWLOCK) 
       where t.lock = 0 
       --and t.Deleted = 0
       order by t.lock
     ) tt;

select * 
from #T t
order by t.ts asc;

drop table #T

通过UPDLOCK，读取和写入之间的值不能改变。

Answer 3

您需要退出数据还是只更新数据？

如果它只是更新：

Update Tablename
   Set Locked  = 'True'
 Where Locked  = 'False' 
   and Deleted = 'False'

给出结果:(在udpate之后添加）

select top 1 ID, TimeStamp, Locked, Deleted 
  from TableName 
 where Locked  = 'True' 
   and Deleted = 'False' 
 order by TimeStamp asc

选择然后在SQL Server 2014中更新记录

3 个答案: