通过加入从CTE中删除

Question

我正在尝试使用sql表实现FIFO队列.

我有以下SQL(修改后发布),连接和参数使用对此过程的工作方式很重要.

With cte as (
   select top(1) q.* from queue q with (readpast)
   inner join MyTable a on q.id = a.myTableID AND myTable.procID = @myParam
   order by q.Data asc
)
delete from cte
    output
      deleted.ID,
      deleted.col1

运行此语句将返回错误'视图或函数'cte'不可更新,因为修改会影响多个基表.

我理解为什么会抛出错误,我无法弄清楚如何解决它.任何建议将不胜感激!

Answer 1

您可以在CTE中使用exists()内部联接而不是内部MyTable联接.

with cte as 
(
  select top(1) q.id,
                q.col1
  from queue q with (readpast)
  where exists(
              select *
              from  MyTable a 
              where  q.id = a.myTableID AND 
                     a.procID = @myParam
              )
  order by q.Data asc
)
delete from cte
output deleted.ID, deleted.col1;

Answer 2

像这样的东西？

With cte as (
   select top(1) q.* from queue q with (readpast)
   inner join MyTable a on q.id = a.myTableID AND myTable.procID = @myParam
   order by q.Data asc
)
delete from queue
Where ID in (Select Id from cte)