<hibernate-mapping ...>
  <class name="Parent" table="TBLPARENT">
    <id name="id" type="double">
      <column name="ID" sql-type="decimal" scale="9" percision="0" />
    </id>

    <set name="children">
      <key column="PID" />
      <one-to-many class="Child" />
      <loader query-ref="children" />
    </set>
  </class>
</hibernate-mapping>

<hibernate-mapping ...>
  <class name="Child" table="TBLCHILD">
    <composite-id name="id" class="ChildID">
      <key-property name="parentID" type="double">
        <column name="PID" sql-type="decimal" scale="9" percision="0" />
      </key-property>
      <key-property name="childID" type="double">
        <column name="SEQ" sql-type="decimal" scale="9" percision="0" />
      </key-property>
    </composite-id>
    <property name="name" type="string">
      <column name="NAME" length="40" sql-type="char" not-null="true"/>
    </property>
  </class>

  <sql-query name="children">
    <load-collection alias="c" role="Parent.children">
      <return-property name="key" column="PID" />
      <return-property name="element">
        <return-column name="PID" />
        <return-column name="SEQ" />
      </return-property>
      <return-property name="element.name" column="NAME" />
    </load-collection>

    select 
      c.PID,
      c.SEQ,
      c.NAME
    from
      TBLCHILD c
    WHERE
      c.PID=?
  </sql-query>
</hibernate-mapping>

CREATE SCHEMA SCHEMA1;

CREATE TABLE SCHEMA1.TBLPARENT(
  ID DECIMAL(9,0) NOT NULL
);

CREATE TABLE SCHEMA1.TBLCHILD(
  PID DECIMAL(9,0) NOT NULL,
  SEQ DECIMAL(9,0) NOT NULL,
  NAME CHAR(40)
);

INSERT INTO SCHEMA1.TBLPARENT VALUES (1);
INSERT INTO SCHEMA1.TBLCHILD VALUES (1,1,'Richard');
INSERT INTO SCHEMA1.TBLCHILD VALUES (1,2,'Sally');
INSERT INTO SCHEMA1.TBLCHILD VALUES (1,3,'Thomas');

INSERT INTO SCHEMA1.TBLPARENT VALUES (2);
INSERT INTO SCHEMA1.TBLCHILD VALUES (2,4,'Harry');
INSERT INTO SCHEMA1.TBLCHILD VALUES (2,5,'Crystal');

INSERT INTO SCHEMA1.TBLPARENT VALUES (3);
INSERT INTO SCHEMA1.TBLCHILD VALUES (3,6,'Jim');

INSERT INTO SCHEMA1.TBLPARENT VALUES (4);

INSERT INTO SCHEMA1.TBLPARENT VALUES (5);
INSERT INTO SCHEMA1.TBLCHILD VALUES (5,7,'George');

2010-08-12 12:19:18,866 TRACE [org.hibernate.engine.query.QueryPlanCache] - <located native-sql query plan in cache (select 
      c.PID,
      c.SEQ,
      c.NAME
    from
      TBLCHILD c
    WHERE
      c.PID=?)>
2010-08-12 12:19:18,866 TRACE [org.hibernate.impl.SessionImpl] - <SQL query: select 
      c.PID,
      c.SEQ,
      c.NAME
    from
      TBLCHILD c
    WHERE
      c.PID=?>
2010-08-12 12:19:18,881 DEBUG [org.hibernate.jdbc.AbstractBatcher] - <about to open PreparedStatement (open PreparedStatements: 0, globally: 0)>
2010-08-12 12:19:18,881 DEBUG [org.hibernate.SQL] - <select 
      c.PID,
      c.SEQ,
      c.NAME
    from
      TBLCHILD c
    WHERE
      c.PID=?>
2010-08-12 12:19:18,881 TRACE [org.hibernate.jdbc.AbstractBatcher] - <preparing statement>
2010-08-12 12:19:18,881 TRACE [org.hibernate.type.DoubleType] - <binding '1.0' to parameter: 1>
2010-08-12 12:19:18,881 TRACE [org.hibernate.loader.Loader] - <Bound [2] parameters total>
2010-08-12 12:19:18,881 DEBUG [org.hibernate.jdbc.AbstractBatcher] - <about to open ResultSet (open ResultSets: 0, globally: 0)>
2010-08-12 12:19:18,881 DEBUG [org.hibernate.loader.Loader] - <result set contains (possibly empty) collection: [forumexample.Parent.children#1.0]>
2010-08-12 12:19:18,881 TRACE [org.hibernate.engine.loading.LoadContexts] - <constructing collection load context for result set [org.apache.derby.client.net.NetResultSet40@f37a62]>
2010-08-12 12:19:18,897 TRACE [org.hibernate.engine.loading.CollectionLoadContext] - <starting attempt to find loading collection [[forumexample.Parent.children#1.0]]>
2010-08-12 12:19:18,897 TRACE [org.hibernate.engine.loading.CollectionLoadContext] - <collection not yet initialized; initializing>
2010-08-12 12:19:18,897 TRACE [org.hibernate.loader.Loader] - <processing result set>
2010-08-12 12:19:18,897 DEBUG [org.hibernate.loader.Loader] - <result set row: 0>
2010-08-12 12:19:18,897 INFO [org.hibernate.type.DoubleType] - <could not read column value from result set: PID1_0_; There is no column named: PID1_0_.  >
2010-08-12 12:19:18,897 DEBUG [org.hibernate.jdbc.AbstractBatcher] - <about to close ResultSet (open ResultSets: 1, globally: 1)>
2010-08-12 12:19:18,897 DEBUG [org.hibernate.jdbc.AbstractBatcher] - <about to close PreparedStatement (open PreparedStatements: 1, globally: 1)>
2010-08-12 12:19:18,897 TRACE [org.hibernate.jdbc.AbstractBatcher] - <closing statement>
2010-08-12 12:19:18,897 DEBUG [org.hibernate.util.JDBCExceptionReporter] - <could not execute query [select 
      c.PID,
      c.SEQ,
      c.NAME
    from
      TBLCHILD c
    WHERE
      c.PID=?]>
java.sql.SQLException: There is no column named: PID1_0_.   
at org.apache.derby.client.am.SQLExceptionFactory40.getSQLException(Unknown Source)
at org.apache.derby.client.am.SqlException.getSQLException(Unknown Source)
at org.apache.derby.client.am.ResultSet.getDouble(Unknown Source)
at org.hibernate.type.DoubleType.get(DoubleType.java:46)
at org.hibernate.type.NullableType.nullSafeGet(NullableType.java:186)
at org.hibernate.type.NullableType.nullSafeGet(NullableType.java:175)
at org.hibernate.type.AbstractType.hydrate(AbstractType.java:105)
at org.hibernate.type.ComponentType.hydrate(ComponentType.java:588)
at org.hibernate.type.ComponentType.nullSafeGet(ComponentType.java:303)
at org.hibernate.loader.Loader.getKeyFromResultSet(Loader.java:1142)
at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:604)
at org.hibernate.loader.Loader.doQuery(Loader.java:745)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:270)
at org.hibernate.loader.Loader.doList(Loader.java:2294)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2172)
at org.hibernate.loader.Loader.list(Loader.java:2167)
at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:316)
at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1832)
at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:165)
at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:179)
at org.hibernate.persister.collection.NamedQueryCollectionInitializer.initialize(NamedQueryCollectionInitializer.java:77)
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:628)
at org.hibernate.event.def.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:83)
at org.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:1853)
at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:366)
at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:108)
at org.hibernate.collection.AbstractPersistentCollection.readSize(AbstractPersistentCollection.java:131)
at org.hibernate.collection.PersistentSet.size(PersistentSet.java:162)
at forumexample.App.main(App.java:25)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:291)
at java.lang.Thread.run(Thread.java:619)
Caused by: org.apache.derby.client.am.SqlException: There is no column named: PID1_0_.   
at org.apache.derby.client.am.ColumnMetaData.findColumnX(Unknown Source)
at org.apache.derby.client.am.ResultSet.findColumnX(Unknown Source)
... 33 more