DECODE Statement help

Question

Hi All,
I have data like this 2 columns GRADE, ITEM_ID
A 001
B 002
C 003
A 006
Z 010
I want to query based on user criteria of what grade they needed. for some reason i need if users choose Z as criteria, i need to list all items with out grade A.
SELECT * FROM my_tbl WHERE grade = DECODE(:userprompt,'A','A','B','B'...'Z', ??);
?? - im missing how to put condition, i tried with '* A' but nothing is listing, obviously it is taking as GRADE = '* Z' and not returning any rows.
Oracle 10 G.
PLS NOTE * = Not equal symbol, for some reason this is not showing up when i post the thread.,
Thanks in ADvance.
Edited by: [email protected] on Sep 4, 2008 10:30 AM

Answer 1

Tony Andrews wrote:
An alternative without DECODE:
SELECT * FROM my_tbl
WHERE ((:userprompt = 'Z' and grade != 'A') or (grade = :userprompt));The above will not work if grade can be null (e.g. item is not graded):
SQL> exec :userprompt := 'Z'
PL/SQL procedure successfully completed.
SQL> with my_tbl as (
  2                  select 'A' grade, '001' item_id from dual union all
  3                  select 'B' grade, '002' item_id from dual union all
  4                  select 'C' grade, '003' item_id from dual union all
  5                  select 'A' grade, '006' item_id from dual union all
  6                  select 'Z' grade, '010' item_id from dual union all
  7                  select null grade, '011' item_id from dual
  8                 )
  9  SELECT * FROM my_tbl
10  WHERE ((:userprompt = 'Z' and grade != 'A') or (grade = :userprompt));
G ITE
B 002
C 003
Z 010To account for null grade:
SQL> exec :userprompt := 'Z'
PL/SQL procedure successfully completed.
SQL> with my_tbl as (
  2                  select 'A' grade, '001' item_id from dual union all
  3                  select 'B' grade, '002' item_id from dual union all
  4                  select 'C' grade, '003' item_id from dual union all
  5                  select 'A' grade, '006' item_id from dual union all
  6                  select 'Z' grade, '010' item_id from dual union all
  7                  select null grade, '011' item_id from dual
  8                 )
  9  SELECT * FROM my_tbl
10  WHERE ((:userprompt = 'Z' and (grade != 'A' or grade is null)) or (grade = :userprompt));
G ITE
B 002
C 003
Z 010
  011SY.