Question

我有两张桌子

table1

id  userid date_t  game  hdigit inside
1   yui    0909    alpha 8      700
2   loi    0809    beta  7      600

table2

id  userid date_t  game  hdigit outside
1   yui    0909    alpha 8       600
2   ron    0809    gama  5      600

I want result like this

id  userid date_t  game  hdigit inside  outside
1   yui    0909    alpha 8      700      600
2   loi    0809    beta  7      600       null
3   ron    0809    gama  5      null      600

我尝试过简单的连接

select table1.userid 
     , table1.date_t 
     , table1.game
     , table1.inside 
     , table2.outside 
  from table1 
     , table2 
 where table1.hdigit = table2.hdigit 
   AND table1.date_t = table2.date_t 
   AND table2.game = table1.game 
   AND table1.userid = table2.userid

显然，它给了我简单的共同价值观，但是如何实现上述任何帮助都会非常感激。

Answer 1

出于您的目的，我认为group by / union all是最佳方法：

select (@rn := @rn + 1) as id, userid, date_t, game, hdigit,
       max(inside) as inside, max(outside) as outside
from ((select userid, date_t, game, hdigit, inside, null as outside
       from table1
      ) union all
      (select userid, date_t, game, hdigit, null, outside
       from table2
      )
     ) t cross join
     (select @rn := 0) params
group by userid, date_t, game, hdigit;

您不希望full join的原因是因为您似乎想要一行用于四个组合键。如果需要一行，group by通常是可行的解决方案。

具有多个条件的mysql中的完全外连接

1 个答案: