0 Replies Latest reply on Jan 16, 2003 6:52 PM by cwele

    Entity relationship & legacy db tables

    cwele Newbie

      I have existing (legacy) DB schema (for simplificity, just two tables, CustomerEJBTable & AccountEJBTable):

      CustomerEJBTable:
      -------------------
      Account_pmPrimaryKey integer,
      userid string

      AccountEJBTable:
      -----------------
      PMPrimaryKey integer,
      Status string

      So, I do not want to allow JBoss to create db tables.

      At the database level, there is no strictly defined foreign key constraint,
      but, in fact, CustomerEJBTable.Account_pmPrimaryKey
      points to the primary key of the AccountEJBTable

      Further, in the customerEJB, I have one cmr field, named 'account'.
      I want to establish one-to-one unidirectional relationship between customerEJB and accountEJB

      Here is extract from ejb-jar.xml & jbosscmp-jdbc.xml:

      ejb-jar.xml
      -------
      <ejb-relation>
      <ejb-relation-name>customerEJB-AccountEJB</ejb-relation-name>

      <ejb-relationship-role>
      customerEJB
      <ejb-relationship-role-name>CustomerEJB</ejb-relationship-role-name>
      One
      <relationship-role-source>
      customerEJB
      <ejb-name>CustomerEJB</ejb-name>
      </relationship-role-source>
      <cmr-field>
      accountEJB
      <cmr-field-name>account</cmr-field-name>
      </cmr-field>
      </ejb-relationship-role>

      <ejb-relationship-role>
      accountEJB <ejb-relationship-role-name>AccountEJB</ejb-relationship-role-name>
      One
      <cascade-delete />
      <relationship-role-source>
      accountEJB
      <ejb-name>AccountEJB</ejb-name>
      </relationship-role-source>
      </ejb-relationship-role>
      </ejb-relation>


      jbosscmp-jdbc.xml
      ------
      <ejb-relation>
      <ejb-relation-name>customerEJB-AccountEJB</ejb-relation-name>
      <foreign-key-mapping />
      <ejb-relationship-role>
      <ejb-relationship-role-name>CustomerEJB</ejb-relationship-role-name>
      </ejb-relationship-role>

      <ejb-relationship-role>
      <ejb-relationship-role-name>AccountEJB</ejb-relationship-role-name>
      <key-fields>
      <key-field>
      <field-name>pMPrimaryKey</field-name>
      <column-name>ACCOUNT_PMPRIMARYKEY</column-name>
      </key-field>
      </key-fields>
      </ejb-relationship-role>
      </ejb-relation>
      --------


      And now, in the CustomerEJB.ejbPostCreate(), I have following code,
      which just creates AccountEJB entity:

      InitialContext ic = new InitialContext();
      AccountLocalHome alh = (AccountLocalHome)
      ic.lookup("java:comp/env/ejb/local/customer/account");
      AccountLocal account = alh.create(AccountLocalHome.Active);
      setAccount(account);
      // where is 'account' - one cmr field in the CustomerEJB


      At this moment, please take a look at following line from my JBoss
      server.log file:

      INSERT INTO ACCOUNTEJBTABLE (PMPRIMARYKEY, STATUS, CustomerEJB_account)
      VALUES (?, ?, ?)

      Please, notice last column in the insert statement: CustomerEJB_account

      Q1: This mysterious column does not exists in AccountEJBTable, so, why
      JBoss attempts to store some value in this column ?

      Of course, my JDBC driver raises SQLException:
      Column unknown
      CUSTOMEREJB_ACCOUNT

      It looks like problem with jbosscmp-jdbc.xml, or not ?

      Q2: What I should to do, to avoid this problem ? I cannot believe that I must to extend my database tables with this strange column names, and unknown types :((
      By the way, I have a lot of legacy database tables....

      ----

      -thanks in advance ....