Question

我的SQL连接查询有问题。我已查找其他建议的答案，并尝试将其应用于我的查询，但它似乎并没有起作用。

我有这个问题：

SELECT SUM(p.quantity)
FROM stocktake_scans p

LEFT JOIN (
SELECT stocktake_area_id
FROM stocktake_areas
WHERE stocktake_id =8592 AND area_checked = 1
)d ON d.stocktake_area_id = p.stocktake_area_id
LEFT JOIN (
    SELECT user_id
    FROM stocktake_scan_edit
    WHERE user_id =46521
    )e ON e.user_id = p.stocktake_staff_id
WHERE p.stocktake_staff_id = 46521

它给了我42的结果，而我只得到6.查询缺少什么？

Answer 1

我认为您可能在联接表中有相同ID的额外记录，在这些记录中，您将从中返回多行，然后计算总和中的错误，请尝试以下操作。

 SELECT SUM(p.quantity) FROM stocktake_scans p LEFT JOIN ( SELECT distinct stocktake_area_id FROM stocktake_areas WHERE stocktake_id =8592 AND area_checked = 1 )d ON d.stocktake_area_id = p.stocktake_area_id LEFT JOIN ( SELECT distinct user_id FROM stocktake_scan_edit WHERE user_id =46521 )e ON e.user_id = p.stocktake_staff_id WHERE p.stocktake_staff_id = 46521

SQL Join提供错误的结果（创建重复项）

1 个答案: