Question

我想计算学费不等于99999.99的实例数，但是我很难让SQL计数功能起作用。我有以下查询：

select  
    year, college,
    case
        when tuition < 99999.99 then 'Other'
        else to_char(tuition)
    end tuition, 
    count(*) as tuition_count
from
    enrolment
group by    
    year, college, tuition
order by    
    year, college, tuition

我期待以下结果，“其他”的计数卷起。

YEAR    COLLEGE     TUITION     TUITION_COUNT
---------------------------------------------
2012    CollegeA    Other       123
2012    CollegeA    99999.99    456

相反，我得到了“其他”的多个实例，每个实例都有一个不同的学费值。

YEAR    COLLEGE     TUITION     TUITION_COUNT
---------------------------------------------
2012    CollegeA    Other       100
2012    CollegeA    Other       20
2012    CollegeA    Other       3
2012    CollegeA    99999.99    456

Answer 1

您需要按（按组声明）分组您想要的内容。像这样：

select  year, college,  case
                          when tuition < 99999.99 then 'Other'
                          else to_char(tuition)
                        end as tuition, count(*) as tuition_count
from enrolment
group by year, college, case
                          when tuition < 99999.99 then 'Other'
                          else to_char(tuition)
                        end
order by year, college, case
                          when tuition < 99999.99 then 'Other'
                          else to_char(tuition)
                        end

这看起来更好：

select  year, college, tuition, count(*) as tuition_count
from 
(
  select  year, college,  case
                            when tuition < 99999.99 then 'Other'
                            else to_char(tuition)
                          end as tuition
  from enrolment
) subselect
group by year, college, tuition
order by year, college, tuition

SQL计数功能不起作用

1 个答案: