SQL子查询与加入混淆

Question

我有一个Access中的数据库（你可以得到它的链接文本 ）。 如果我跑

SELECT DISTINCT Spl.Spl_No, Spl.Spl_Name
FROM Spl INNER JOIN Del 
   ON Spl.Spl_No = Del.Spl_No
WHERE Del.Item_Name <> 'Compass'

它提供了从未提供指南针的供应商的名称。 但是，您可以使用子查询来执行此操作。 到目前为止，我和其他一些人都未能做到正确。

我确实接近以下，直到我们添加了更多的供应商，然后它停止了工作

SELECT SPL.SPL_Name
FROM SPL
LEFT JOIN DEL ON Del.SPL_No = SPL.SPL_No
WHERE (DEL.Item_Name<>"Compass") OR (DEL.Item_Name IS NULL)
GROUP BY SPL.SPL_Name
HAVING COUNT(DEL.SPL_No) = 0

所以问题是：这可能与子查询有关。

Answer 1

我想我会选择：

SELECT SELECT Spl_No, Spl_Name
FROM Spl
WHERE Spl_No NOT IN 
  (SELECT Spl_No FROM Del
   WHERE Item_Name = 'Compass')

Answer 2

你的意思是这样的吗？

SELECT SPL.SPL_Name
FROM SPL
WHERE NOT SPL.SPL_no IN 
 (SELECT SPL_no FROM DEL WHERE DEL.Item_Name = "Compass") 

Answer 3

SELECT Spl_No
     , Spl_Name
  FROM Spl
 WHERE NOT EXISTS( SELECT *
                     FROM Del
                    WHERE Del.Spl_no = Spl.Spl_no
                      AND Item_name  = 'Compass' )

Answer 4

如果Access存在.....

SELECT SPL.SPL_Name FROM SPL WHERE NOT EXISTS（SELECT 1 FROM DEL WHERE Del.SPL_No = SPL.SPL_No AND（DEL.Item_Name ='Compass'））

Answer 5

它非常接近你用英语怎么说

“给我那些没有交付指南针的供应商。”

Select [Stuff]
From Spl S
Where Not Exists
   (Select * From Del
    Where Spl_no = S.Spl_no 
       And Item_name  = 'Compass')

编辑：没有存在，您可以使用Count（*）= 0

Select [Stuff]
From Spl S
Where 
   (Select Count(*) From Del
    Where Spl_no = S.Spl_no 
       And Item_name  = 'Compass') = 0

Answer 6

从未交付指南针的供应商：

SELECT Spl.Spl_No, Spl.Spl_Name
FROM Spl
LEFT JOIN Del ON Del.Spl_No = Spl.Spl_No AND Del.Item_Name = 'Compass'
WHERE Del.Item_Name IS NULL

并使用子查询：

SELECT Spl_No, Spl_Name
FROM Spl
WHERE Spl_No IN 
  (
    SELECT Spl_No
    FROM Del
    GROUP BY Spl_No, Item_Name
    WHERE Item_Name = 'Compass'
    HAVING COUNT(*) = 0
  )

Answer 7

这是你在找什么？

SELECT
   SPL.SPL_name
FROM
   SPL
WHERE
   SPL.SPL_No NOT IN
   (
      SELECT SPL_No FROM DEL WHERE DEL.Item_Name <> "Compass"
   )