不可以使用case when 的列名进行group by，如：
select count(1)/7 as "平均违法数量", to_char(wfsj, 'yyyy-MM-dd' ) as time, case when (to_char(wfsj, 'hh24')) between 00 and 04 then '00-04时' when (to_char(wfsj, 'hh24')) between 04 and 08 then '04-08时' when (to_char(wfsj, 'hh24')) between 08 and 12 then '08-12时' when (to_char(wfsj, 'hh24')) between 12 and 16 then '12-16时' when (to_char(wfsj, 'hh24')) between 16 and 20 then '16-20时' when (to_char(wfsj, 'hh24')) between 20 and 24 then '20-24时' end as "违法时间"fromvio_violation where wfsj >= trunc(sysdate - 7)group by "违法时间"；
正确sql：
select count(1)/7 as "平均违法数量", to_char(wfsj, 'yyyy-MM-dd' ) as time, case when (to_char(wfsj, 'hh24')) between 00 and 04 then '00-04时' when (to_char(wfsj, 'hh24')) between 04 and 08 then '04-08时' when (to_char(wfsj, 'hh24')) between 08 and 12 then '08-12时' when (to_char(wfsj, 'hh24')) between 12 and 16 then '12-16时' when (to_char(wfsj, 'hh24')) between 16 and 20 then '16-20时' when (to_char(wfsj, 'hh24')) between 20 and 24 then '20-24时' end as "违法时间"fromvio_violation where wfsj >= trunc(sysdate - 7)group by wfsj；
转载于:https://www.cnblogs.com/ww5566/p/11124851.html
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