Many-to-many probelm help

[shabarish vai]

hi all,
i have an application where you can create category and add products and save to Database.
i have order table and product table where you can create product (all product created goes here) and i also have link table order_product table.
now my problem is if i place a order which has for instance with 2 products i want only order and link table to be saved like,

order table ------ order_product------ product table
1 1 2 1
2 1 3 2
3 2 2 3

so when i submit order I'll have product id's i.e 2,3,2 using these product ID i need to update link table and order table.
is there a way to do this? please help

[Jim Hoglund]

Your problem description is not clear to me. Can you
describe the table contents in more detail? Thanks.

Jim ... ...

[shabarish vai]

sorry
order table ------
1
2
3
order_product- this is link table with order_id and product_id
1 2
1 3
2 2
product table
1
2
3
wen i submit order i'll have product id's so i need to save product details like order id 1 will have product id 1,2.

[shabarish vai]

hi can anyone help me in this problem as struck and need it urgently

[James Sutherland]

Sounds like a basic ManyToMany relationship. Don't see an issue? What ORM are you using?
In JPA you just use a ManyToMany mapping.

[shabarish vai]

thanks for the reply the problem here is wen i save order object then order,order_product,product table will be updated i already have product id so only thing i need to update is order,order_product am using hibernate and MSQL, i dont want product table to be updated

[Jim Hoglund]

What do you have so far? Maybe it's time to look at some code.

Jim ... ...

[shabarish vai]

  public class mantTOmanysave {

    public static void main(String ar[]) {
        Transaction transaction =null;
        Session session = HibernateUtil.currentSession();
        transaction = session.beginTransaction();
        try {
            Order orderBO = new Order();
            orderBO.setOrderName("shab1");
            Product productBO = new Product();
            Set set = new HashSet();
           // productBO.setProductname("Product1");
            set.add(productBO);
            orderBO.setProducts(set);
            session.save(orderBO);
            transaction.commit();
        }
        catch(Exception e) {
            System.err.println("Exception in main "+e.getMessage());
            e.printStackTrace();
        }
        finally
        {
            HibernateUtil.closeSession();
        }
    }
}  

  <hibernate-mapping>
  <class catalog="test" name="persistence.Order" table="order">
    <id name="orderId" type="java.lang.Integer">
      <column name="order_id"/>
      <generator class="identity"/>
    </id>
    <property name="orderName" type="string">
      <column length="20" name="orderName"/>
    </property>
    <set cascade="all" name="products" table="order_product">
      <key>
        <column name="orderID" not-null="true"/>
      </key>
      <many-to-many entity-name="persistence.Product">
        <column name="productID" not-null="true"/>
      </many-to-many>
    </set>
  </class>
</hibernate-mapping>  

  <hibernate-mapping>
  <class catalog="test" name="persistence.Product" table="product">
    <id name="productid" type="java.lang.Integer">
      <column name="productid"/>
      <generator class="identity"/>
    </id>
    <property name="productname" type="string">
      <column length="20" name="productname"/>
    </property>
    <property name="productDesc" type="string" column="productDesc" length="20"/>
    <set inverse="true" name="orders" table="order_product">
      <key>
        <column name="productID" not-null="true"/>
      </key>
      <many-to-many entity-name="persistence.Order">
        <column name="orderID" not-null="true"/>
      </many-to-many>
    </set>
  </class>
</hibernate-mapping>