Question

我有如下表格

CatID| Total_Amount | Amount_paying |IsCompleted
-----|--------------|---------------|------------
CA01 |  2000        |    1700       |  0

在此表中，我必须检查Total_Amount和amount_paying是否相同？其中total_amount是固定的，amount_paying将在每个插入语句后获得最大化。

所以如果我插入一条记录

    CatID| Total_Amount | Amount_paying |IsCompleted
    -----|--------------|---------------|------------
    CA01 |  2000        |    1700       |  0
    CA01 | 2000         |    300        |  1

我支付300，所以Total_Amount = Amount_Paying和IsCompleted = 1

UPDATE tbl
        SET is_completed = CASE WHEN SUM(amount_paying) = Total_Amount THEN 1 ELSE 0 END
        WHERE tbl.branch_id =@branchid AND CatID=@catid

给予An aggregate may not appear in the set list of an UPDATE statement.

Answer 1

如果数据库引擎在UPDATE语句中允许相同的目标表：

UPDATE tbl
SET IsCompleted = IF((SELECT SUM(Amount_paying) FROM tbl WHERE CatID = 'CA01') >= Total_Amount, 1, 0)
WHERE CatID = 'CA01';

但是，例如，使用MySQL，您将获得Query Error: Error: ER_UPDATE_TABLE_USED。

所以，下面应该有效：

UPDATE tbl AS t
JOIN (
  SELECT 
    CatID, 
    SUM(Amount_paying) AS totalAP
  FROM tbl 
  WHERE CatID = 'CA01'
  GROUP BY CatID
) AS t2 ON (t2.CatID = t.CatID)
SET t.IsCompleted = IF(t2.totalAP >= t.Total_Amount, 1, 0)
WHERE t.CatID = 'CA01';

这是 demo fiddle 。

注意：在您自己的示例中，您尝试设置is_completed。根据您的表格，它应为IsCompleted。

同时更新和检查

1 个答案: