Subquery factoring

Question

hello
Is it a rule that the subquery should always be followed with a select statement.
I am using it as follows
WITH subquery_this AS
SELECT col_name1, col_name2, col_name3, ROW_NUMBER() OVER ( PARTITION BY col_name3
ORDER BY col_name2 DESC )
AS S
FROM zs
WHERE col_name2 = something
Update sometable
SET col_name5 = (select col_name2 from subquery_this where sometable2.col_name1= subquery_this.col_name1)
My question is is it necessary that the "with" subquery should be followed by a select statement. As in my case it is followed with an update statement.
Also if I am using this in a procedure, where this should be placed.
-> In the BEGIN section or
-> After IS and before BEGIN i.e in DECLARE section of subprocedure.
Edited by: user6287828 on Mar 12, 2009 6:39 PM

Answer 1

WITH is a feature only of the SELECT statement. But you can use SELECT in INSERT/UPDATE/DELETE statements.
Here's a trivial example:
SQL> update emp
  2  set    job = ( with subq as (select 'LAYABOUT' newjob from dual)
  3                 select newjob from subq)
  4  where empno = 7934
  5  ;
1 row updated.
SQL> select * from emp where empno = 7934;
               EMPNO ENAME      JOB                        MGR HIREDATE
                7934 MILLER     LAYABOUT                  7782 23-JAN-1982 00:00:00