Case statement in where clause with In clause

Question

I tried using case statement in the where clause, which needs to filter my where condition based on the parameter value passed to my procedure, but it didn't worked

where case when p_parameter ='Y' then 'Y' else ('Y','N') END in Hidden_flag_column

Answer 1

Try

where 
case when p_parameter ='Y' 
     then case when Hidden_flag_column = 'Y' then 1 else 0 end
     else case when Hidden_flag_column in ('Y','N') then 1 else 0 end 
END = 1

Example with p_parameter = 'Y' as well as 'N' and Hidden_flag_column = 'N'.

select * from dual
where 
case when 'N' ='Y' 
     then case when 'N' = 'Y' then 1 else 0 end
     else case when 'N' in ('Y','N') then 1 else 0 end 
END = 1

gives 1 row while

select * from dual
where 
case when 'Y' ='Y' 
     then case when 'N' = 'Y' then 1 else 0 end
     else case when 'N' in ('Y','N') then 1 else 0 end 
END = 1

gives 0 rows.