為什么 MySQL View 和同一個 View 的底層 SELECT 查詢返回不同的結果？

Question

我可以在此問題上提供一些幫助，在此問題中，我試圖生成一組結果，將余額提前並結轉余額。

MySQL 腳本：

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)

當我運行 SELECT * FROM vwbalances 時，我得到了這個（錯誤的結果）：

當我運行用於創建 VIEW 的完整 SELECT 語句時，我得到了這個（正確的結果）：

提前致謝。

Answer 1

您發布的查詢甚至不應該工作。

• usrid 是最外層選擇中的別名。 它在您的子查詢中不可用。
• 除非你有一列名為year東西year( tx . date_created ) < year也不應該工作
• 您在外部查詢和子查詢中使用相同的表別名。 這也應該是不可能的。 如果是，那可能就是你得到奇怪結果的原因。

除此之外，您不必多次執行基本相同的查詢。 您可以將查詢縮短為如下所示：

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`)

（當然，這個奇怪的year對你有用）

Answer 2

以下腳本已正常工作。 感謝所有幫助和提示：

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);