Oracle SQL Case语句检查SQL脚本的结果

Question

I have a very huge query, this query has a lot of Case statements within the select statment. Right now I'm struggling with the following case

select .... 
   case 
      when (select name from location where document = xyz) != ''
      then <do something>
      else <do something else>
   end
.
.
.

How should I check the condition in the above when statement? It seems to not work right now as it is always entering the else block. All I'm trying to check is if the query returns anything or just null.

Answer 1

As suggested by the @OldProgrammer I've modified it to the following. It worked.

select .... 
   case 
      when (select name from location where document = xyz) is not null 
      then <do something>
      else <do something else>
   end
.
.
.