Question

您好我正在编写一些需要if的东西才能从数据库中检索结果。

情况是如果interacterID不是NULL然后按它过滤，请参阅下面的

SELECT *
FROM status
WHERE type != "3"
AND userID = "'.$userID.'"
AND 
(
    interacterID IN ( #IF interacterID is null I want to skip this AND
        SELECT userID
        FROM userFriends
        WHERE (
            userFriends.userID = "'.$currentUserID.'"
            OR userFriends.interacterID = "'.$currentUserID.'"
        )
        AND status = "1"
    )
)
ORDER BY addedDate DESC
LIMIT 1

提前感谢您的帮助。

Answer 1

如果我正确读到这个，我不确定你需要一个IF（which can be done）。一个简单的IS NULL和OR可以用于两种情况：

SELECT *
FROM status
WHERE type != "3"
AND userID = "'.$userID.'"
AND 
(
    interacterID IS NULL OR interacterID IN (
        SELECT userID
        FROM userFriends
        WHERE (
            userFriends.userID = "'.$currentUserID.'"
            OR userFriends.interacterID = "'.$currentUserID.'"
        )
        AND status = "1"
    )
)
ORDER BY addedDate DESC
LIMIT 1

Answer 2

SELECT *
FROM status
WHERE type != "3"
AND userID = "'.$userID.'"
AND 
(
interacterID IS NOT NULL  (
    SELECT userID
    FROM userFriends
    WHERE (
        userFriends.userID = "'.$currentUserID.'"
        OR userFriends.interacterID = "'.$currentUserID.'"
    )
    AND status = "1"
)
  )
  ORDER BY addedDate DESC
  LIMIT 1

如果interacterID为null，则代码将不会执行

在MYSQL查询中使用If

2 个答案: