如何通过以下查询使用按功能分组？答案

【问题标题】：How can I use group by function with below query?如何通过以下查询使用按功能分组？
【发布时间】：2014-05-08 13:44:38
【问题描述】：

如何通过以下查询使用分组功能？

实际上我尝试加入（内连接）两个包含 2 个字段的表。

没关系：

t1.fiels6 = t2.field7

这在内部连接函数中不起作用。因此我在 where 函数中使用了它：

t1.field8 = SUBSTRING(t2.field9,1,INSTR(t2.field9,'-') - 1) 
and (INSTR(t2.field9,'-') - 1) < 14 
and (INSTR(t2.field9,'-') - 1) > 0

我的主要目标是获取每组 t2.field2 的 avg((t1.field3 * t2.field4)) 和 stddev((t1.field3 * t2.field4))

select 
    t1.field1 as f1, t2.field2 as f2,(t1.field3 * t2.field4) as f5 
from 
    pub.table1 t1, pub.table2 t2 
where 
    t1.fiels6 = t2.field7 
    and t1.field6 = 'XXX' 
    and t1.field8 = SUBSTRING(t2.field9,1,INSTR(t2.field9,'-') - 1) 
    and (INSTR(t2.field9,'-') - 1) < 14 and (INSTR(t2.field9,'-') - 1) > 0

【问题讨论】：

标签： sql group-by

【解决方案1】：

将你拥有的内容移动到内部选择和分组 --

select f2, avg(calced), atddev(calced)
from
(
  select 
    t1.field1 as f1, 
    t2.field2 as f2,
    (t1.field3 * t2.field4) as calced 
  from pub.table1 t1
  join pub.table2 t2 on t1.fiels6 = t2.field7 
                    and (INSTR(t2.field9,'-') - 1) < 14 
                    and (INSTR(t2.field9,'-') - 1) > 0
                    and t1.field8 = SUBSTRING(t2.field9,1,INSTR(t2.field9,'-') - 1) 
  where t1.field6 = 'XXX' 
) t
group by f2

【讨论】：