Using Decode in Order By clause

Question

Hi all,
I've a prblem with the DECODE in ORDER BY clause
Could you please advise if I did something wrong with my sort order.
Actually,I've a store procedure which gather all information from several tables and return with a resultset.
Therefore I just post an example table_resultset instead of lenghthy StoreProc in forum
/* table contain the column need to be sort on the resultset */
create table table_sort (sortnum,sortname) as
select 1553, 'IDNO' from dual union all
select 1231, 'IDNAME' from dual union all
select 1001, 'CREDATE' from dual;
/* a sample of some information that resultset return by a storeproc */
create table table_resultset (idno,idname,credate) as
select 1111, 'SORT ORDER', sysdate-7 from dual union all
select 54555, 'NEED A TEST CASE', sysdate+5 from dual union all
select 10012, 'BEYOND THE LIMIT', sysdate from dual union all
select 10522, 'CONCENTRATION', sysdate+20 from dual union all
select 01231, 'A VALIDATION', sysdate-3 from dual;
/* this select statement similar to execute a storeproc with s decode in the ORDER BY clause */
select * from table_resultset
order by decode((select ltrim(rtrim(sortname)) from table_sort where sortnum=1231),'IDNO',1,'IDNAME',2,3);
OR
select * from table_resultset
order by case (select ltrim(rtrim(sortname)) from table_sort where sortnum=1231)
when 'IDNO' then 1
when 'IDNAME' then 2
else 3
end;
Thanks.

Answer 1

Thanks for the tip Samb ... :)
I got it ... all sort field must be same datatype.
SQL> create table table_sort (sortnum,sortname) as
2 select 1553, 'IDNO' from dual union all
3 select 1231, 'IDNAME' from dual union all
4 select 1001, 'CREDATE' from dual;
Table created.
SQL> create table table_resultset (idno,idname,credate) as
2 select 1111, 'SORT ORDER', sysdate-7 from dual union all
3 select 54555, 'NEED A TEST CASE', sysdate+5 from dual union all
4 select 10012, 'BEYOND THE LIMIT', sysdate from dual union all
5 select 10522, 'CONCENTRATION', sysdate+20 from dual union all
6 select 01231, 'A VALIDATION', sysdate-3 from dual;
Table created.
SQL> select * from table_resultset;
IDNO IDNAME CREDATE
1111 SORT ORDER 08-07-03
54555 NEED A TEST CASE 08-07-15
10012 BEYOND THE LIMIT 08-07-10
10522 CONCENTRATION 08-07-30
1231 A VALIDATION 08-07-07
SQL> select * from table_sort;
SORTNUM SORTNAM
1553 IDNO
1231 IDNAME
1001 CREDATE
if I want to sort the resultset by the column IDNAME of table_resultset then
SQL> select * from table_resultset
2 order by decode((select ltrim(rtrim(sortname)) from table_sort
3 where sortnum=1231),'IDNO',to_char(idno),'IDNAME',idname,to_char(credate,'yyyymmdd'));
IDNO IDNAME CREDATE
1231 A VALIDATION 08-07-07
10012 BEYOND THE LIMIT 08-07-10
10522 CONCENTRATION 08-07-30
54555 NEED A TEST CASE 08-07-15
1111 SORT ORDER 08-07-03
if I want to sort the resultset by the column CREDATE of table_resultset then
SQL> select * from table_resultset
2 order by decode((select ltrim(rtrim(sortname)) from table_sort
3 where sortnum=1001),'IDNO',to_char(idno),'IDNAME',idname,to_char(credate,'yyyymmdd'));
IDNO IDNAME CREDATE
1111 SORT ORDER 08-07-03
1231 A VALIDATION 08-07-07
10012 BEYOND THE LIMIT 08-07-10
54555 NEED A TEST CASE 08-07-15
10522 CONCENTRATION 08-07-30
But if I want to sort the resultset by the column IDNO of table_resultset then I've a problem due to the field converted into character, and the field IDNO define as number(9) of a table in production. therefore I've to find a solution when that field convert into character must be same length in order to sort IDNO correctly. As you can see from below
SQL> select * from table_resultset
2 order by decode((select ltrim(rtrim(sortname)) from table_sort
3 where sortnum=1553),'IDNO',to_char(idno),'IDNAME',idname,to_char(credate,'yyyymmdd'));
IDNO IDNAME CREDATE
10012 BEYOND THE LIMIT 08-07-10
10522 CONCENTRATION 08-07-30
1111 SORT ORDER 08-07-03
1231 A VALIDATION 08-07-07
54555 NEED A TEST CASE 08-07-15
your suggestion always welcome.
Thanks,
DT.