Question

是否可以将带有NOT IN运算符的子查询转换为连接？我需要使用连接

的查询

SELECT *
FROM Contacts
WHERE ContactIntID NOT IN(
    SELECT LinkToIntID
    FROM Requirements
    WHERE Requirements.uuJobStatus = 'Open')

Answer 1

是

SELECT c.*
FROM Contacts c
LEFT JOIN 
  (SELECT LinkToIntID FROM Requirements WHERE uuJobStatus='Open') r 
  ON (c.ContactIntID=r.LinkToIntID)
WHERE r.LinkToIntID IS NULL

并简化：

SELECT c.*
FROM Contacts c
LEFT JOIN 
  Requirements r 
  ON  r.uuJobStatus = 'Open'
  AND c.ContactIntID = r.LinkToIntID
WHERE r.LinkToIntID IS NULL

Answer 2

使用非存在通常比使用LEFT JOIN更好。有了上面的答案，联系人将加入所有记录，无论它们是否匹配，然后使用IS NULL子句将其过滤掉。

SELECT *
FROM Contacts c
WHERE NOT EXISTS
(
    SELECT 1
    FROM Requirements r
    WHERE Requirements.uuJobStatus = 'Open'
    AND ContractIntID = r.LinkToIntID
)

编辑：意识到你想要一个非子查询，但值得注意我的回复：）

Answer 3

SELECT *
FROM Contacts C LEFT JOIN Requirements R
ON C.CommonField = R.CommonField
WHERE R.CommonField IS NULL AND R.uuJobStatus = 'Open'

使用“not in”运算符转换子查询以加入

3 个答案: