如何编写自联接查询? [英] How to write selfjoin query?

问题描述

MID-名称-PID
2 ---- A ----- 0
3 ---- M ----- 0
4 ---- N ----- 0
11 --- B ----- 2
12 --- C ----- 2
13 --- D ----- 3
14 --- E ----- 2
31 --- Z ---- 11
32 --- Y ---- 12
33 --- X ---- 12
34 --- W ---- 13
35 --- V ---- 14

上面是表结构.
我想编写一个查询(条件将为PID = 2)，将从中获取以下值

11
12
14
31
32
33
35

有人可以帮我写这个查询吗?
在此先感谢.

MID -- Name-- PID
2 ---- A ----- 0
3 ---- M ----- 0
4 ---- N ----- 0
11 --- B ----- 2
12 --- C ----- 2
13 --- D ----- 3
14 --- E ----- 2
31 --- Z ---- 11
32 --- Y ---- 12
33 --- X ---- 12
34 --- W ---- 13
35 --- V ---- 14

Above is the table structure.
I want to write a single query (where condition will be PID=2) from which this following value will be fetched

11
12
14
31
32
33
35

Can anyone help me to write this query?
Thanks in advance.

推荐答案

从表名中选择t1.MID作为t1
在t1.PID = t2.PID上将表名加入为t2
其中t1.PID = 2

select t1.MID from tablename as t1
join tablename as t2 on t1.PID = t2.PID
where t1.PID = 2

select Mid from urtable where pid=2

查询什么问题.它会给你同样的结果.如果要编写自连接查询，请使用解决方案1.

what problem in query. it will give you same result. no need of selfjoin if you want to write self join query use solution 1.

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