如何在Case语句中使用If条件？

Question

以下是我的查询。这是正确的吗？

SQL> select case when value in (1000) then null
2  when user in ('ABC') then user
3  when area in ('DENVER') then
4  if value = 2000 then 'Service1'
5  else value = 3000 then 'Service2'
6  end if
7  else null
8  end as num_code from service_usoc_ref;
if prin = 2000 then 'Omaha'
*
ERROR at line 4:
ORA-00905: missing keyword

请帮帮我。

Answer 1

你可以放另一个案例或使用解码（如@madhu建议的那样）：

select case 
  when value in (1000) then null
  when user in ('ABC') then user
  when area in ('DENVER') then
    case when value = 2000 then 'Service1'
         when value = 3000 then 'Service2'
    end 
  else null
  end as num_code 
from service_usoc_ref;

Answer 2

这可以帮到你

 select  case when value in (1000) then null
                         when user in ('ABC') then user
                       when area in ('DENVER') then
decode( value, 2000 , 'Service1',3000 , 'Service2', NULL)  num_code 
from service_usoc_ref;