SELECT如果一行中的2个单元格相等（MySQL）

Question

试图尽可能简单地展示它。 如果连续2个单元格相等（MySQL）

，我想选择主题

表

---------------------------------------------
Subject  ---  username  --- Lastpostername 
---------------------------------------------
subject A --- user1    ---  user3
Subject B --- user2    ---  user3
Subject C --- user3    ---  user3
Subject D --- user4    ---  user1

结果我需要选择主题C因果用户名和lastpostername相等 （按ID排序DESC，因此最新的第一个）

Answer 1

假设您的表名是'abc'，然后您可以创建以下查询，

SELECT Subject from abc WHERE abc.username = abc.Lastpostername ORDER BY abc.id DESC;

Answer 2

SELECT t.subject
FROM tab AS t
WHERE t.username = t.Lastpostername
ORDER BY t.id DESC

Answer 3

SELECT Subject from Table WHERE username = Lastpostername ORDER BY id desc;