Java开发日常-Oracle中group by与order by配合使用

现象

• 在group by 和order by配合使用执行oracle数据库查询时，出现异常

原SQL语句

select  SDEPARTMENT, SCONTRACT_NAME, avg(DCONTRACT_VALUE) DCONTRACT_VALUE
from HY_PROJECT_ACCOUNTBOOK 
where SPROJECT_ID = 'EERIU651453'
group by SCONTRACT_NAME, SDEPARTMENT
order by INUM desc;

异常

ORA-00979: 不是 GROUP BY 表达式
00979. 00000 -  "not a GROUP BY expression"

原因

• order by 排序的对象是group by 分组之后的数据，很显然没有INUM字段

• 假设没有order by 排序的需求

select  SDEPARTMENT, SCONTRACT_NAME, avg(DCONTRACT_VALUE) DCONTRACT_VALUE
from HY_PROJECT_ACCOUNTBOOK 
where SPROJECT_ID = 'EERIU651453'
group by SCONTRACT_NAME, SDEPARTMENT;

• 新增按INUM排序的需求(group by 字句中新增INUM字段)

select min(INUM) INUM,  SDEPARTMENT, SCONTRACT_NAME, avg(DCONTRACT_VALUE) DCONTRACT_VALUE
from HY_PROJECT_ACCOUNTBOOK 
where SPROJECT_ID = 'EERIU651453'
 group by SCONTRACT_NAME, SDEPARTMENT
order by INUM desc;