ColumnResult (Java EE 5 SDK)

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Java EE 5 SDK

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摘要: REQUIRED | OPTIONAL

详细信息: ELEMENT

javax.persistence Annotation Type ColumnResult

@Target(value={}) @Retention(value=RUNTIME) public @interface ColumnResult

References name of a column in the SELECT clause of a SQL query - i.e., column alias, if applicable. Scalar result types can be included in the query result by specifying this annotation in the metadata.


 Example:
   Query q = em.createNativeQuery(
       "SELECT o.id AS order_id, " +
           "o.quantity AS order_quantity, " +
           "o.item AS order_item, " + 
           "i.name AS item_name, " +
         "FROM Order o, Item i " +
         "WHERE (order_quantity > 25) AND (order_item = i.id)",
       "OrderResults");

   @SqlResultSetMapping(name="OrderResults",
       entities={
           @EntityResult(entityClass=com.acme.Order.class, fields={
               @FieldResult(name="id", column="order_id"),
               @FieldResult(name="quantity", column="order_quantity"),
               @FieldResult(name="item", column="order_item")})},
       columns={
           @ColumnResult(name="item_name")}
       )