I have two tables CAT and MICE
CAT table
(cat_id int primary key,
name varchar(16),
sex char(1),
weight double)

MICE
(mice_id int primary key,
name varchar(16),
eatenby int)

I want to perform an outer join using CAT, MICE. field in MICE table is a foreign key that refernces CAT.cat_id. I don't want to use MiddleGen and XDoclet. I would like to corresponding to the given tables. Once this is done I would like to formulate the outer join query using CAT and MICE tables.

I am using the following code:

Cat.java

package net.sf.hibernate.examples.quickstart;

public class Cat {

private int id;
private String name;
private char sex;
private float weight;

public Cat() {
}
public int getId() {
return id;
}
private void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public char getSex() {
return sex;
}
public void setSex(char sex) {
this.sex = sex;
}
public float getWeight() {
return weight;
}
public void setWeight(float weight) {
this.weight = weight;
}

}

Mice.java

package net.sf.hibernate.examples.quickstart;

public class Mice {

private int id;
private String name;
private Cat cat;

public Mice() {
}
public int getId() {
return id;
}
private void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Cat getCat() {
return cat;
}
public void setCat(Cat cat) {
this.cat = cat;
}

}

Mice.hbm.xml

<hibernate-mapping>

<class name="net.sf.hibernate.examples.quickstart.Mice" table="MICE">

<id name="id" type="integer" unsaved-value="null" >
<column name="MICE_ID" sql-type="int" not-null="true"/>
<generator class="increment"/>
</id>

<property name="name">
<column name="NAME" length="16" not-null="true"/>
</property>

<many-to-one name="cat" class="net.sf.hibernate.examples.quickstart.Cat" column="cat_id"/>

</class>

</hibernate-mapping>

Cat.hbm.xml


<hibernate-mapping>

<class name="net.sf.hibernate.examples.quickstart.Cat" table="CAT">

<id name="id" type="integer" unsaved-value="null" >
<column name="CAT_ID" sql-type="int" not-null="true"/>
<generator class="increment"/>
</id>

<property name="name">
<column name="NAME" length="16" not-null="true"/>
</property>

<property name="sex"/>

<property name="weight"/>

</class>

</hibernate-mapping>

After this in a file i am trying to call this query:

Query q1 = sess.createQuery(
"select cat.name " +
"from Cat as cat, Mice as mice " +
"outer join mice.cat as cat"
);

The code is comiling successfully. When i run the main file it gives and then the stack trace.[/quote]

I am unable to solve this problem. Plz suggest code changes required.....

Thanks......

Why didn't you add the fllowing code snippet in the Cat.hbm.xml and Cat.java?

public class Cat {

private HashSet mices=new HashSet();

....

public Set getMices(){
return mices;
}

public void setMices(Set mices){
this.mices=mices;
}

....
}


Cat.hbm.xml

<hibernate-mapping>
<class name="net.sf.hibernate.examples.quickstart.Cat" table="CAT">
<id name="id" type="integer" unsaved-value="null" >
<column name="CAT_ID" sql-type="int" not-null="true"/>
<generator class="increment"/>
</id>
<property name="name">
<column name="NAME" length="16" not-null="true"/>
</property>
<property name="sex"/>
<property name="weight"/>
<set name="mices" inverse="true" lazy="true" cascade="all" outer-join="true">
<key column="eatenby"/>
<one-to-many class="net.sf.hibernate.examples.quickstart.Mice"/>
</set>

</class>

your hql code shoud be:

select cat from Cat cat

I don't known if i really understand your meaning.

bcoz i need a join on CAT and MICE tables....

amjn.

don't follow the design of my classes. i am not sure if i am in the right direction...

i need to execute a outer join on CAT and MICE table and eatenby is a foreign key, as shown in the table layout.

could u suggest chnages now.... why do we need Set class????

Hi gs_1481:

In fact,it is standard one-to-many relationship between Cat table and Mice table.So you must represent the bidirectional relationship in Cat.hbm.xml and Mice.hbm.xml at first,separately initialize a Set object containing many Mice objects in the Cat class and a cat object reference in the Mice class.

I strongly suggest you look through the hibernate reference or hibernate in action before go about write code with hibernate.I am beginner with hibernate too,and only known a little about hibernate.

Thanks...
I have solved the problem.... i got the lead from ur first reply on Set interface... basically i was not able to get the point that CAT maps MICE as 1 : m relationship...
for that we need to have a collection of mice in Cat.java and a refence to cat in Mice.java... this is the way i visualize it....

Then on i formulated the outer join query and was able to execute it...

Thanks frnd... if possible lets meet tomorrow on yahoo chat

I am facing a new problem now.

My joins are working fine, i am able to insert data in the CAT table but i am unable to insert data in the MICE table.

Thanks....