web server - Borland Technical Publications

Support for ORDER BY
Support for ORDER BY
The EJB 2.0 Specification supports three SQL clauses in EJB-QL: SELECT, FROM, and
WHERE.
The Borland CMP engine also supports the SQL clause ORDER BY in the same EJB-QL
statement, provided it is placed after the WHERE clause. This is done in the standard ejbjar.xml
deployment descriptor in the entity. For example, the following EJB-
QL statement selects distinct objects from a Customer Bean and orders them by the
LNAME field:
findCustomerByNumber
SELECT Distinct Object(c) from CustomerBean c WHERE c.no > 1000 ORDER
BY c.LNAME
You can specify either ASC (ascending) or (DESC) descending in your EJB-QL as
well. If you do not specify either, the results will be ordered ascending by default.
For example, consider the following table:
The query:
Support for GROUP BY
NAME DEPARTMENT SALARY HIRE DATE
Timmy Twitfuller Mail Room 1000 1/1/01
Sam Mackey The Closet with the Light Out 800 1/2/02
Ralph Ossum Coffee Room 900 1/4/01
SELECT OBJECT(e) FROM EMPLOYEE e ORDER BY e.HIRE_DATE
will produce the following result:
NAME DEPARTMENT SALARY HIRE DATE
Timmy Twitfuller Mail Room 1000 1/1/01
Ralph Ossum Coffee Room 900 1/4/01
Sam Mackey The Closet with the Light Out 800 1/2/02
The GROUP BY clause is used to group rows in the result table prior to the SELECT
operation being performed. Consider the following table:
NAME DEPARTMENT SALARY HIRE DATE
Mike Miller Mail Room 1200 11/18/99
Timmy Twitfuller Mail Room 1000 1/1/01
Buddy Coffee Room 1000 4/13/97
Sam Mackey The Closet with the Light Out 800 1/2/02
Todd Whitmore The Closet with the Light Out 900 4/12/01
Ralph Ossum Coffee Room 900 1/4/01
156 BES Developer’s Guide