求和一列并将其更新到我的表格中？

Question

DECLARE  @cnt int
select @cnt = 2

SUM工作正常！

SELECT SUM(Count) AS cnt FROM VF_CasINV_Cost
where (K = 'K') and (CalendarYear = 2010) AND (Item# < 99999992)

但没有数据更新到表，@ cnt = 0？

UPDATE VF_CasINV_Cost
SET [Count] = @cnt
WHERE (K = 'K') and (CalendarYear = 2010) AND (Item# = 99999992)

Answer 1

@cnt和cnt是两回事。一个是服务器端变量，一个是表字段。 MySQL中完全不同的存储区域。如果您希望查询更新VARIABLE，那么您需要执行

SELECT @cnt := SUM(Count) AS cnt 
...