具有多个条件的 case 语句

Question

I would like to do a count of active participants based on a field called program_code grouped by the name of the manager. But I also want a count of something else in the same query where three conditions have to be met.

select manager_name, 
       sum (case program_code when 'F' then 1 else 0 end) as F, 
       sum (case program_code 
              when 'FS' then 1 
              else 0 
            end) 
  from table1 
 where status='AC' 
 group by manager_name

But I want a third count of all participants who have a possible_ind='Y' AND date_attended is not null AND status_cd='P'

I can't put that in a case statement with all those conditions. Is there a way I can do it? Would it need to be a sub-query in the select clause? I have tried it with a sub-query in the select clause, but it doesn't group it by manager_name .

select manager_name, 
       sum (program_code when 'F' then 1 else 0 end) as F, 
       sum (case program_code 
              when 'FS' then 1 
              else 0 end), 
           (select count(*) 
              from table1 
             where possible_ind='Y' 
               and date_attended is not null 
               and status_cd='P') as NEW 
  from table1 
 where status='AC' 
 group by manager_name

Answer 1

You can omit the expression in your case statement and make your "when" statements more detailed.

select manager_name, 
sum (program_code when 'F' then 1 else 0 end) as F, 
sum (case program_code 
    when 'FS' then 1 
    else 0 end), 
sum (case
    when possible_ind='Y' 
        and date_attended is not null 
        and status_cd='P' then 1 else 0 end) as NEW 
from table1 
where status='AC' 
group by manager_name

Refer to Oracle's example for more information.