Need help on order by in PL/SQL

Question

Hi all,
I know this problem would have occurred a lot of times before, but me being a beginner want to know all the possible solution for this one.Now I am having a procedure in which I am declaring a cursor to select rows from a table
create or replace procedure call_me(sortstring IN Varchar2(200))
IS
cursor cur is
select * from EMP order by (sortstring);
BEGIN
for rec in cur
Loop
DBMS_OUTPUT.PUT_LINE(cur.EMPNAME)
END LOOP;
END;
Assume the EMP table has
EMPID,EMPNAME,EMPCITY,EMPDEPT as its fields
I am calling the procedure like
exec procedure_call('EMPCITY,EMPDEPT')
but I get an unsorted output, worse still
exec procedure_call('EMPCITY')
itself is not working.If I hard-code the order by columns in the query it is working, but when I pass it as argument it is not working.Please help me resolve this issue.

Answer 1

In your case,
satyaki>
satyaki>select * from v$version;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - Prod
PL/SQL Release 10.2.0.3.0 - Production
CORE    10.2.0.3.0      Production
TNS for 32-bit Windows: Version 10.2.0.3.0 - Production
NLSRTL Version 10.2.0.3.0 - Production
Elapsed: 00:00:00.33
satyaki>
satyaki>select * from emp order by '&str';
Enter value for str: empno
old   1: select * from emp order by '&str'
new   1: select * from emp order by 'empno'
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
      7777 SOURAV     SLS                  14-SEP-08      45000       3400         10
      7499 Travor     SALESMAN        7698 20-FEB-81       1600        300         30
      7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7782 CLARK      MANAGER         7839 09-JUN-81       4450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7839 KING       PRESIDENT            17-NOV-81       7000                    10
      7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
      7900 JAMES      CLERK           7698 03-DEC-81        950                    30
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
13 rows selected.
Elapsed: 00:00:01.00
satyaki>In our case,
satyaki>select * from emp order by &str;
Enter value for str: empno
old   1: select * from emp order by &str
new   1: select * from emp order by empno
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
      7499 Travor     SALESMAN        7698 20-FEB-81       1600        300         30
      7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7777 SOURAV     SLS                  14-SEP-08      45000       3400         10
      7782 CLARK      MANAGER         7839 09-JUN-81       4450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7839 KING       PRESIDENT            17-NOV-81       7000                    10
      7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
      7900 JAMES      CLERK           7698 03-DEC-81        950                    30
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
13 rows selected.
Elapsed: 00:00:00.31
satyaki>/
Enter value for str: empno,job
old   1: select * from emp order by &str
new   1: select * from emp order by empno,job
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
      7499 Travor     SALESMAN        7698 20-FEB-81       1600        300         30
      7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7777 SOURAV     SLS                  14-SEP-08      45000       3400         10
      7782 CLARK      MANAGER         7839 09-JUN-81       4450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7839 KING       PRESIDENT            17-NOV-81       7000                    10
      7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
      7900 JAMES      CLERK           7698 03-DEC-81        950                    30
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
13 rows selected.
Elapsed: 00:00:00.18
satyaki>So, capitalizing this ->
satyaki>
satyaki>declare
  2    cursor cur
  3    is
  4      select *
  5      from EMP
  6      order by &sortstring;
  7     
  8    rec cur%rowtype;
  9  begin
10   for rec in cur
11    Loop
12      DBMS_OUTPUT.PUT_LINE(rec.ENAME);
13    END LOOP;
14  END;
15  /
Enter value for sortstring: empno,job
old   6:     order by &sortstring;
new   6:     order by empno,job;
Travor
WARD
JONES
MARTIN
BLAKE
SOURAV
CLARK
SCOTT
KING
TURNER
ADAMS
JAMES
FORD
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.84
satyaki>Got my point?
Regards.
Satyaki De.