user manual

Chapter 17: EJB-QL and Data Access Support 179

Chapter

Chapter17EJB-QL and Data Access

Support

EJB-QL allows you to specify queries in an object oriented query language,

EJB-QL. The Borland CMP engine translates these queries into SQL queries.

The Borland Enterprise Server provides some extensions to the EJB-QL

functionality described in the Sun Microsystems EJB 2.x Specification.

Important For documentation updates, go to www.borland.com/techpubs/bes.

Selecting a CMP Field or Collection of CMP Fields

When only one cmp-field of an otherwise large EJB is required, you can use

EJB-QL to select a single instance of collection of that cmp-field. Using EJB-

QL in this way improves application performance by eliminating the need to

load an entire EJB. For example, this query method selects only the balance

field from the Account table:

<query>

<query-method>

<method-name>ejbSelectBalanceOfAccountLineItem</method-name>

<method-params>

<method-param>java.lang.Long</method-param>

</method-params>

</query-method>

<result-type-mapping>Local</result-type-mapping>

<ejb-ql>SELECT l.balance FROM Account a, IN (a.accountLineItem) l WHERE