尝试创建SQL查询,如果字段条目符合条件或null,则在其中读取字段中,它将进入值读取的值,如果不是,则会跳过该行的整体选择。
SELECT a.name, b.age
CASE
WHEN a.birthday = b.birthday THEN vlaue?
WHEN a.birthday != b.birthday THEN skip?
ELSE is null THEN null
END AS birthday
FROM information a, tracking b
WHERE a.name = b.name
因此,如果出生日期匹配或无效,它将输入名称和年龄,但是如果出生日期不匹配,则根本不会输入名称和年龄。
您应该在此处使用此
SELECT a.name, b.age
CASE
WHEN a.birthday = b.birthday THEN 'value'
ELSE null
END AS birthday
FROM information a
INNER JOIN tracking b ON a.name = b.name
WHERE a.birthday != b.birthday
(您应该使用说明符号符号..更读取)
,或者如果您在不匹配时也需要左JOIN
SELECT a.name, b.age
CASE
WHEN a.birthday = b.birthday THEN 'value'
ELSE null
END AS birthday
FROM information a
LEFT JOIN tracking b ON a.name = b.name
WHERE a.birthday != b.birthday