为什么 MySQL View 和同一个 View 的底层 SELECT 查询返回不同的结果？

Question

我可以在此问题上提供一些帮助，在此问题中，我试图生成一组结果，将余额提前并结转余额。

MySQL 脚本：

CREATE OR REPLACE VIEW vwbalances AS
SELECT th.user_id usrid
     , YEAR(th.date_created) year 
     , IFNULL(
              (SELECT SUM(tx.amount) 
                 FROM transdetail tx 
                 JOIN transhdr th 
                   ON th.thdr_id = tx.thdr_id
                 JOIN users u 
                   ON th.user_id = u.user_id 
                 JOIN transtype tt 
                   ON tt.ttype_id = tx.ttype_id 
                WHERE tx.ttype_id in (2,9,11) 
                  AND u.user_id = usrid 
                  and YEAR(tx.date_created) < year
              )
           ,0) bal_bfwd
     , SUM(td.amount) bal_ytd
     , ifnull(
              (SELECT SUM(ty.amount) 
                 FROM transdetail ty 
                 JOIN transhdr th
                   ON th.thdr_id = ty.thdr_id
                 JOIN users u 
                   ON th.user_id = u.user_id 
                 JOIN transtype tt 
                   ON tt.ttype_id = ty.ttype_id 
                WHERE ty.ttype_id in (2,9,11) 
                  AND u.user_id = usrid 
                  AND YEAR(ty.date_created) <= year
              )
           ,0) bal_cfwd
  FROM transdetail td 
  JOIN transhdr th 
    ON th.thdr_id = td.thdr_id
  JOIN users u 
    ON th.user_id = u.user_id 
  JOIN transtype tt 
    ON tt.ttype_id = td.ttype_id 
 WHERE td.ttype_id in (2,9,11) 
 GROUP 
    BY th.user_id
     , YEAR(th.date_created)

当我运行 SELECT * FROM vwbalances 时，我得到了这个（错误的结果）：

当我运行用于创建 VIEW 的完整 SELECT 语句时，我得到了这个（正确的结果）：

提前致谢。

Answer 1

您发布的查询甚至不应该工作。

• usrid 是最外层选择中的别名。 它在您的子查询中不可用。
• 除非你有一列名为year东西year( tx . date_created ) < year也不应该工作
• 您在外部查询和子查询中使用相同的表别名。 这也应该是不可能的。 如果是，那可能就是你得到奇怪结果的原因。

除此之外，您不必多次执行基本相同的查询。 您可以将查询缩短为如下所示：

SELECT `th`.`user_id` AS usrid
    , year(`th`.`date_created`) AS 'year'
sum(if(year(td.date_created`) < year, amount, 0)) as bal_ytd,
sum(if(year(td.date_created`) <= year, amount, 0)) as bal_cfwd
FROM `transdetail` `td`
JOIN `transhdr` `th` ON `th`.`thdr_id` = `td`.`thdr_id`
JOIN `users` `u` ON `th`.`user_id` = `u`.`user_id`
JOIN `transtype` `tt` ON `tt`.`ttype_id` = `td`.`ttype_id`
WHERE `td`.`ttype_id` IN (2, 9, 11)
GROUP BY `th`.`user_id`
    , year(`th`.`date_created`)

（当然，这个奇怪的year对你有用）

Answer 2

以下脚本已正常工作。 感谢所有帮助和提示：

CREATE OR REPLACE VIEW vwbalances AS
SELECT tho.user_id AS usrid, YEAR(td.date_created) AS 'year' 

, ROUND(IFNULL((SELECT sum(tx.amount) FROM transdetail tx 
JOIN transhdr th ON th.thdr_id = tx.thdr_id
JOIN users u ON th.user_id = u.user_id 
JOIN transtype tt ON tt.ttype_id = tx.ttype_id 
WHERE tx.ttype_id IN (2,9,11) AND u.user_id = tho.user_id AND 
YEAR(tx.date_created) < YEAR(td.date_created) ),0),2) AS 
bal_bfwd

, round(sum(td.amount),2) AS bal_ytd

, ROUND(IFNULL((select SUM(ty.amount) FROM transdetail ty 
JOIN transhdr th on th.thdr_id = ty.thdr_id
JOIN users u ON th.user_id = u.user_id 
JOIN transtype tt ON tt.ttype_id = ty.ttype_id 
WHERE ty.ttype_id IN (2,9,11) AND u.user_id = tho.user_id AND 
YEAR(ty.date_created) <= YEAR(td.date_created)),0),2) AS 
bal_cfwd

FROM transdetail td JOIN transhdr tho ON tho.thdr_id = 
td.thdr_id
JOIN users u ON tho.user_id = u.user_id 
JOIN transtype tt on tt.ttype_id = td.ttype_id 
WHERE td.ttype_id IN (2,9,11) 
GROUP BY tho.user_id, YEAR(td.date_created);