Hibernate createalias() method is used to create the joins. When I am calling s.iterator() method hibernate is generating another select query to get the child record? As per my understanding it generates the single select query to get the both parent and child records using join.

Criteria ct = sn.createCriteria(Vendor.class);
Criteria ct1= ct.createAlias("children", "cust");
List<Vendor> l = ct.list();
Iterator<Vendor> i = l.iterator();
while (i.hasNext()) {
Vendor v = (Vendor) i.next();
System.out.println("name " + v.getVendorname());
Set<Customer> s = v.getChildren();
Iterator<Customer> it = s.iterator();
while (it.hasNext()) {
Customer c = it.next();
System.out.println("custname " + c.getCustomername());
}
}
Mapping files;
<hibernate-mapping>
<class name="com.criteria.example.Vendor" table="vendor">
<id name="vendorid" column="vid">
<generator class="native" />
</id>
<property name="vendorname" type="string">
<column name="vname" length="10" not-null="true" />
</property>
<set name="children" inverse="false" cascade="all" lazy="false">
<key column="vendid" not-null="true"/>

<one-to-many class="com.criteria.example.Customer"/>
</set>

</class>
</hibernate-mapping>
<hibernate-mapping>
<class name="com.criteria.example.Customer" table="customer" >
<id name="customerid" column="cid">
<generator class="native" />
</id>
<property name="customername" type="string">
<column name="cname" length="10" not-null="true" />
</property>
</class>
</hibernate-mapping>

Try it like this: