在MYSQL中执行LEFT OUTER JOIN时插入零而不是NULL [英] Inserting a Zero instead of NULL while performing LEFT OUTER JOIN in MYSQL

问题描述

有没有办法在两个表上执行LEFT OUTER JOIN时插入零而不是NULL?

Is there a way to insert a zero instead of NULL while performing LEFT OUTER JOIN on two tables?

假设我有这样的查询:

SELECT * FROM
(SELECT uID from Class) T1
LEFT OUTER JOIN
(SELECT pID from University) T2
ON T1.uID = T2.pID
CASE WHEN T1.uID IS NULL
    THEN 0
ELSE T1.uID
END AS uID`

如果我错了，请纠正我

推荐答案

CASE WHEN a.fieldname IS NULL 
       THEN 0
       ELSE a.fieldname
END AS fieldname

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