IF ELSE in postgresql function

I am trying to create a function which is as follows

create function public.getSomething(
        value1 integer
    )
      returns table (
             id integer,
             name varchar(20)
    
              ) as
    $$
    BEGIN
    
        IF value1 = 0 THEN
        
            select a.id, b.name from table1 a inner join table2 b on a.Something = b.Something where 
            a.column = something and b.column = something;
            
        END IF;
    
        IF value1 = 1 THEN
        
            select a.id, b.name from table1 a inner join table2 b on a.Something = b.Something where 
            a.column = something and b.column = something;
            
        END IF;
    
    END;
            
    $$ language SQL;

But when I am trying to Create, I am getting the following error

ERROR:  syntax error at or near "if" 

I tried changing the Language from SQL to plpgsql. But this time I am getting

Error: query has no destination for result data
Hint: if you want to discard the results of a select use perform instead

then I replaced the Select with Perform. This time the function is created but when I am calling it There is no result!!

What am I doing wrong? Is there any alternative? I am Using postgres version 12.3