mysql - 在 mysql 中连接两个表时出现错误，如 "Unknown column ' m.machinenumber' in 'on clause' "?

Question

连接两个表时，我执行了一个查询，但它没有正确显示第二个表数据，而是显示垃圾值..

我使用的查询是，

select p.machinenumber,
max(case when (p.shift)=1 then xxxx end) s1_xxxx,
max(case when (p.shift)=2 then xxxx end) s2_xxxx,
avg(case when (p.shift)=1 then yyyy end) s1_yyyy ,
avg(case when (p.shift)=2 then yyyy end) s2_yyyy 
from pdata p
inner  join (select  count(case when (shift)=1 and (ename)=1  then ename end) s1_wa,
count(case when (shift)=1 and (ename)=2 then errorname end) s1_we,
count(case when (shift)=2 and (ename)=1 then errorname end) s2_wa,
count(case when (shift)=2 and (ename)=2 then ename end) s2_we,
count(case when (shift)=1 and (ename)=0 then ename end) s1_merror,
count(case when (shift)=2 and (ename)=0 then ename end) s2_merror  from mstop)m
on p.mnumber=m.mnumber
where date(p.proddate)='2013-02-25'; 

请解决这个问题？？

Answer 1

您还需要为 m.mnumber 返回 mnumber。在 mstop 表的内部连接中，您还需要返回 mnumber 以便根据 mnumber 连接它。

inner  join (select  count(case when (shift)=1 and (ename)=1  then ename end) s1_wa,
count(case when (shift)=1 and (ename)=2 then errorname end) s1_we,
count(case when (shift)=2 and (ename)=1 then errorname end) s2_wa,
count(case when (shift)=2 and (ename)=2 then ename end) s2_we,
count(case when (shift)=1 and (ename)=0 then ename end) s1_merror,
count(case when (shift)=2 and (ename)=0 then ename end) s2_merror,
     mnumber  from mstop)m
on p.mnumber=m.mnumber