Case when

Question

hello
what wrong with this query...
1 SELECT COUNT(*) FROM AGR_MSTR WHERE (CASE WHEN 1=1 THEN
2 'AGR_STATUS='||CHR(39)||'L'||CHR(39)
3 ELSE
4 'AGR_STATUS='||CHR(39)||'P'||CHR(39)
5* END)
6 /
END)
ERROR at line 5:
ORA-00920: invalid relational operator
executed perfectly if i run same query in select clause,
SELEct (CASE WHEN 1=1 THEN
'AGR_STATUS='||CHR(39)||'L'||CHR(39)
ELSE
'AGR_STATUS='||CHR(39)||'P'||CHR(39)
END) from dual

Answer 1

SQL> select count(*)
  2    from emp
  3   where (case when 1=1 then 'job='||chr(39)||'CLERK'||chr(39)
  4          else 'job='||chr(39)||'MANAGER'||chr(39)
  5          end)
  6  /
        end)
FOUT in regel 5:
.ORA-00920: invalid relational operatorThis doesn't work because basically you are saying "select count(*) from emp where <function>". You can have a function in the where clause, but it should be a boolean predicate like in "select count(*) from emp where <function> = <value>".
SQL> select (case when 1=1 then 'job='||chr(39)||'CLERK'||chr(39)
  2          else 'job='||chr(39)||'MANAGER'||chr(39)
  3          end)
  4    from dual
  5  /
(CASEWHEN1=1T
job='CLERK'
1 rij is geselecteerd.So the function itself is OK.
SQL> select count(*)
  2    from emp
  3   where (case when 1=1 then 'job='||chr(39)||'CLERK'||chr(39)
  4          else 'job='||chr(39)||'MANAGER'||chr(39)
  5          end) = 'job=''CLERK'''
  6  /
                              COUNT(*)
                                    14
1 rij is geselecteerd.Now it is of the form "where <function> = <value>" and it returns results.
But you probably need this one:
SQL> select count(*)
  2    from emp
  3   where job = case when 1=1 then 'CLERK' else 'MANAGER' end
  4  /
                              COUNT(*)
                                     4
1 rij is geselecteerd.Regards,
Rob.