Question

我如何获得每小时的计数？

select count_hr_1, count_hr_2, count_hr_3 from db.table where year=2018 and month=01 and day=02 and hour=01 OR hour=02 OR hour=03;

此SQL /查询可能无效，但我想获得小时1,2,3的计数

Answer 1

select sum(case when hour = 1 then 1 else 0 end) as count_hr_1, 
       sum(case when hour = 2 then 1 else 0 end) as count_hr_2, 
       sum(case when hour = 3 then 1 else 0 end) as count_hr_3
from db.table 
where year = 2018 
and month = 1 
and day = 2 
and hour in (1,2,3)

Answer 2

如果您能够将结果集处理为多行而不是一行，则可以使用GROUP BY：

select hour, count(*)
  from db.table
  where
    year = 2018
    and month = 1
    and day = 2
    and hour in (1, 2, 3)
  group by hour

根据小时SQL计算

2 个答案: