How do I execute different SELECT statements based on a CASE

Question

I am facing a problem in executing queries with CASE statement. Based on my condition,(for eg. length), I want to execute different SQL statement.

Problematic sample query is as follows:

select case 
    when char_length('19480821') = 8
        then select count(1) from Patient
    when char_length('19480821')=10
        then select count(1) from Doctor 
end

Exception:

[Error] Script lines: 1-5 --------------------------
Incorrect syntax near the keyword 'select'.
Msg: 156, Level: 15, State: 2
Server: sunsrv4z7, Line: 2

I am not able to correct the syntax. I am getting the string for char_length as input from the user. How can I fire queries based on certain condition? Is CASE the right choice ? Or do I have to use any other thing.

Answer 1

Just put opening and closing bracket around select statement resolve you problem

select 
    case when 
        char_length('19480821')=8 then 
            (select count(1) from Patient )
        when 
        char_length('19480821')=10 then 
            (select count(1) from Doctor )
      end