大家好,我有下表:
ID - COL_A - COL_B
我需要检索所有 COL_A = 1 的记录,并且 COL_A = 1 的 COL_B 不得有其他 COL_A = 2 的记录。
你能帮我吗?
谢谢
最佳答案
这是一个不存在
的情况,我认为:
SELECT *
FROM mytable AS t1
WHERE COL_A = 1 AND
NOT EXISTS (SELECT 1
FROM mytable
WHERE t1.COL_B = t2.COL_B AND COL_A = 2)
您还可以使用LEFT JOIN
:
SELECT t1.*
FROM mytable AS t1
LEFT JOIN mytable AS t2 ON t1.COL_B = t2.COL_B AND t2.COL_A = 2
WHERE t1.COL_A = 1 AND t2.COL_A IS NULL
关于mysql - 选择特定字段没有其他记录的行,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/35851635/