Not Sure why this is not working

Question

hi all,
Version details :
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
PL/SQL Release 11.2.0.2.0 - Production
"CORE     11.2.0.2.0     Production"
TNS for Solaris: Version 11.2.0.2.0 - Production
NLSRTL Version 11.2.0.2.0 - Production
Select * From Dual
Where 'A' In (Decode( 'A','A','''A'''
  ||','
  ||'''B''','C','C'));
Result :
   no rows
Select * From Dual
Where 'C' In (Decode( 'C','A','''A'''
  ||','
  ||'''B''','C','C'));
Result :
Dummy
   XPlease let me know why this is working like this ..
Problem:
When the input is 'A' then condition should be 'A' in ('A','B')
When the input is 'C' then condition should be 'C' in ('C')
Thanks,
P Prakash
Edited by: prakash on Feb 4, 2013 10:41 PM

Answer 1

Your first query
Select * From Dual Where 'A' In (Decode( 'A','A','''A'''||','||'''B''','C','C'));This would be evalueated like this
select * from dual where 'A' = '''A'''||','||'''B'''And your second query
Select * From Dual Where 'C' In (Decode( 'C','A','''A'''||','||'''B''','C','C'));Thiw would be evaluated like this
select * from dual where 'C' = 'C'You cannot pass value for IN operater as comma seperated string. The entire string will be passed as a single value. Each value in an in operator is a seperate variable and need to be passed sperately.
select * from dual where 'A' in ('A', 'B') is not the same as
select * from dual where 'A' in ('''A'''||','||'''B''')