sql if elsif and sql function

select (
case (select count(1) from BY_TASK_WORKITEM where task_id='34424141') 
  when 0 then '没有完成的记录'
  else
 (select count(1) from BY_TASK_WORKITEM where task_id='34424141' and completion='已完成')/
 (select count(1) from BY_TASK_WORKITEM where task_id='34424141' ) *100 ||''
  end 
)  as  donetotal from dual

 

 

create or replace function getTotal(taskId in number) return varchar2 is
  num1 number;
  num2 number;
  resultStr varchar2(128);
  begin
     select count(1) into num1 from BY_TASK_WORKITEM where task_id=taskId;
     select count(1) into num2 from BY_TASK_WORKITEM where task_id=taskId and completion='已完成';
     if (num1=0  or num2 =0) then 
       resultStr:='没有完成的记录';
     else
       resultStr:=(num2/num1)*100||'%';
     end if;
     return  resultStr;
  end;

-- 调用
select (gettotal(26129857))from dual