水平合并两个查询结果

Question

我有一个表scott2，我从中运行两个查询。

第一个查询是：

SELECT rateid, sysuserid, appraiserid, category, rate FROM `scott2` WHERE sysuserid = appraiserid and sysuserid = '20' group by category order by category;

其结果是：

第二个是：

SELECT rateid, sysuserid, appraiserid, category, sum(rate) FROM `scott2` WHERE sysuserid != appraiserid and sysuserid = '20' group by category order by category asc;

其结果是：

我想将结果合并为以下格式。我希望查询2中的sumrate列与查询1中的rate列相邻。

  

SYSUSERID |类别| RATE |求和

我尝试过使用此子查询，但无济于事。

SELECT sysuserid, category, 
(SELECT rate FROM `scott2` WHERE sysuserid = appraiserid and sysuserid = '20' group by category order by category asc) as 'rate',
(select sum(rate) from scott2 where sysuserid != appraiserid and sysuserid = '20' group by category order by category asc) as 'sumrate'
from scott2
group by category
order by category asc;

错误：

  

子查询返回1行以上

我如何实现自己想要的？

Answer 1

在主查询中，您未在其中指定“ sysuserid = 20”，并且使用的是无效的“ sysuserid ='20'”。同样，当您在主查询中使用“按类别分组”时，您应该在条件od子查询所在的位置进行分类。

要限制子查询第二项仅包含一个结果，可以使用limit。虽然限制无效。您应该在逻辑上验证“ sysuserid” +“ category”组合的唯一结果。

您可以尝试以下查询。

SELECT sysuserid, category, 
(SELECT sc_i.rate FROM `scott2` as sc_i WHERE sc_i.sysuserid = sc_i.appraiserid and sc_i.sysuserid = sc.sysuserid and sc_i.category = sc.category limit 1) as 'rate',
(SELECT sc_i.rate FROM `scott2` as sc_i WHERE sc_i.sysuserid <> sc_i.appraiserid and sc_i.sysuserid = sc.sysuserid and sc_i.category = sc.category limit 1) as 'sumrate'
from scott2 as sc
where sysuserid = 20
group by sysuserid, category
order by category asc;

Answer 2

尝试此代码

SELECT t1.sysuserid, t1.category, t1.rate , 
    (select sum(rate) from scott2 t2 where t2.category = t1.category AND sysuserid != appraiserid and sysuserid = '20' group by category) as sumrate

from scott2 t1
group by t1.category
order by t1.category asc;