Question

我需要通过UPDATE为表中的组“汇总”位值。因此，如果组中的某一行设置为true，则需要将组中的其他行设置为true。

例如，我有一个这样的表：

GroupID | Type   | BitA | BitB
------------------------------
   1    | Parent |  0   |  0
   1    | Child  |  1   |  0
   2    | Parent |  0   |  0
   2    | Child  |  1   |  1
   2    | Child  |  0   |  1
   3    | Parent |  0   |  0
   3    | Child  |  0   |  0

在UPDATE语句之后的预期结果将是：

GroupID | Type   | BitA | BitB
------------------------------
   1    | Parent |  1   |  0
   1    | Child  |  1   |  0
   2    | Parent |  1   |  1
   2    | Child  |  1   |  1
   2    | Child  |  0   |  1
   3    | Parent |  0   |  0
   3    | Child  |  0   |  0

由于第1组的子级的BitA设置为true，因此父级也应设置为true。

我唯一能找到的就是首先将位转换为int以便将其聚合到组中，但是好像我要钻进兔子洞了。

SELECT
   MAX(CAST(BitA as int)),
   MAX(CAST(BitB as int))
FROM MyTable
WHERE Type = 'Child'
GROUP BY GroupID

有更简单的方法吗？

Answer 1

您似乎想基于子级设置父级标志：

with toupdate as (
      select t.*,
             max(BitA) over (partition by groupid) as max_bitA,
             max(BitB) over (partition by groupid) as max_bitB
      from mytable t
     )
update toupdate
    set BitA = max_BitA,
        BitB = max_BitB
    where BitA <> max_BitA or BitB <> max_BitB;

如果您输入的比特确实是bit，则需要进行一些转换：

with toupdate as (
      select t.*,
             convert(bit, max(convert(int, BitA)) over (partition by groupid)) as max_bitA,
             convert(bit, max(convert(int, BitB)) over (partition by groupid)) as max_bitB
      from mytable t
     )
update toupdate
    set BitA = max_BitA,
        BitB = max_BitB
    where BitA <> max_BitA or BitB <> max_BitB;

Answer 2

这可以为您提供所需的东西...

UPDATE M1
SET M1.BITA = 1,
    M1.BITB = 1
FROM MYTABLE M1
WHERE EXISTS
(
SELECT 1
  FROM MYTABLE M2
 WHERE M2.GroupID = M1.GoupID
      AND
     (
        M2.BITA = 1
       OR M2.BITB = 1
  )
);

如何为组设置汇总位值

2 个答案: