Single Query for getting total no of records N getting records from a selected range

Question

Hi,
Got the below query:
SELECT a.*, rowid FROM (SELECT name, postcode FROM Tbl ORDER BY name asc)a WHERE ROWNUM <=30
MINUS
SELECT b.*, rowid FROM (SELECT name, postcode FROM Tbl ORDER BY name asc) b WHERE ROWNUM <= 10
Though I got the results right, I also want to know the total no of records from "SELECT name, postcode FROM Tbl ORDER BY name asc". Does anyone knows how to do it in a single query?
Thanks.

Answer 1

hi Carol
The following output may help you.
SQL> l
1 select * from emp where (rowid,0) in (select rowid,mod(rownum,10)-rownum from emp)
2 minus
3* select * from emp where (rowid,0) in (select rowid,mod(rownum,6)-rownum from emp)
SQL> /
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
7839 KING PRESIDENT 17-NOV-81 5000 10
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7876 ADAMS CLERK 7788 12-JAN-83 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
The above query fetches the 6,7,8,9th records only.
Well my suggestion would be not to use ROWNUM directly in where clause since it changes dynamically. it is not a fixed value. for example pls see the result.
SQL> select rownum,empno,ename,sal,job from emp where sal > 3000;
ROWNUM EMPNO ENAME SAL JOB
1 7839 KING 5000 PRESIDENT
SQL> select rownum,empno,ename,sal,job from emp where sal > 1000;
ROWNUM EMPNO ENAME SAL JOB
1 7566 JONES 2975 MANAGER
2 7654 MARTIN 1250 SALESMAN
3 7698 BLAKE 2850 MANAGER
4 7782 CLARK 2450 MANAGER
5 7788 SCOTT 3000 ANALYST
6 7839 KING 5000 PRESIDENT
7 7844 TURNER 1500 SALESMAN
8 7876 ADAMS 1100 CLERK
9 7902 FORD 3000 ANALYST
10 7934 MILLER 1300 CLERK
10 rows selected.
SQL> select * from emp where rownum = 1;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
7566 JONES MANAGER 7839 02-APR-81 2975 20
The record of employee KING is getting the rownum differently.
My understanding (out of my little knowledge) is the rownum values are assigned to the records only after the records are read physically and after applying the conditions(without rownum). Then the row numbers (rownum) is assigned to the records. Hence the rownum is not constant to a record since it is a dynamic value.
Well i would like to know the suggestions of the ORACLE EXPERTS here in the discussion forum.
If my finding is correct then OK if not Pls excuse me and pls give the correct solution
Regards
Prakash Eranki
[email protected]