SatyaCodes

Hibernate- Named Queries

Hibernate- Named Queries

if we want to execute the same queries for multiple times in our program then we can use the Named Queries mechanism

  • In this Named Queries concept, we use some name for the query configuration, and that name will be used whenever the same query is required to execute

  • If you want to create Named Query, in hibernate mapping file we need to configure a query by putting some name for it.

  • For HQL, we need to use <query name="query_name"> to configure query

    <query name="bankHQLQuery">
<![CDATA[from BankBo b where b.balance>:bal ]]>
</query>

  • For Native SQL, we need to use <sql-queryname="query_name"> to configure query

    <sql-query name="bankNativeQuery">
  select * from Employee
</sql-query>

  • In our main program, we need to use getNamedQuery() given by session interface, for getting the Query reference and we need to execute that query by calling list()

    Query qry = session.getNamedQuery("Name given in hib-mapping-xml");
qry.setParameter("bal",new Integer(3000));
List l = qry.list();


Example 1 : HQL Named Query Example

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration SYSTEM
"hibernate-configuration-3.0.dtd">

<hibernate-configuration>
	<session-factory>
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/smlcodes</property>
		<property name="hibernate.connection.username">root</property>
		<property name="hibernate.connection.password">root</property>
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
		<property name="show_sql">true</property>
		<property name="hbm2ddl.auto">update</property>
		<mapping resource="EmployeeBo.hbm.xml" />
		<mapping resource="BankBo.hbm.xml" />
	</session-factory>
</hibernate-configuration>

BankBo.java

public class BankBo {
	private int accno;
	private String accname;
	private double balance;
	//Setters & getters

BankBo.hbm.xml

<hibernate-mapping>
	<class name="hql.BankBo" table="bank">
		<id name="accno" column="accno" />
		<property name="accname" column="accname" />
		<property name="balance" column="balance" />
	</class>

	<query name="bankHQLQuery">
<![CDATA[from hql.BankBo b where b.balance>:bal ]]>
	</query>
</hibernate-mapping>

HQLNamedQuery.java

package namedQuery;
public class HQLNamedQuery {
 public static void main(String[] args) {
 // 1.Load Configuration
 Configuration cfg = new Configuration();
 cfg.configure("hibernate.cfg.xml");
 
 // 2.Create Session
 SessionFactory sf = cfg.buildSessionFactory();
 Session session = sf.openSession();

 System.out.println("HQL-NamedQuery Example\n----------");
 Query qry = session.getNamedQuery("bankHQLQuery");
 qry.setParameter("bal", new Double(3000));
 List list = qry.list();
 Iterator it = list.iterator();
 while (it.hasNext()) {
 BankBo bo = (BankBo) it.next();
 System.out.println(bo.getAccname() + ", " + bo.getBalance());
 }  
 session.close();
 sf.close();
 }
}
-----------------------------
HQL-NamedQuery Example
-----------------------------
Hibernate: select bankbo0_.accno as accno1_, bankbo0_.accname as accname1_, bankbo0_.balance as balance1_ from bank bankbo0_ where bankbo0_.balance>?
Rakesh, 4000.0
CHANDU, 5000.0


Example 2 : Native SQL Named Query Example

EmployeeBo.java

package bo;
public class EmployeeBo {
	 private int eid;
	 private String name;
	 private String address;	
  //Setters & getters
}

EmployeeBo.hbm.xml

<hibernate-mapping>
	<class name="bo.EmployeeBo" table="employee">
		<id name="eid" column="eid">
			<generator class="uuid" />
		</id>
		<property name="name" column="name" />
		<property name="address" column="address" />
	</class>

	<sql-query name="employeeNativeQuery">
		select * from Employee
	</sql-query>
</hibernate-mapping>

NamedQueryDemo.java

package namedQuery;
public class NamedQueryDemo {
 public static void main(String[] args) {
 // 1.Load Configuration
 Configuration cfg = new Configuration();
 cfg.configure("hibernate.cfg.xml");
 
 // 2.Create Session
 SessionFactory sf = cfg.buildSessionFactory();
 Session session = sf.openSession();
 Query qry = session.getNamedQuery("employeeNativeQuery");
 List list = qry.list();
 Iterator it = list.iterator();
 while (it.hasNext()) {
 	Object o[] = (Object[]) it.next();
 	System.out.println(o[0] + ", " + o[1] + ", " + o[2]);
 }
 session.close();
 sf.close();
 }
}
HQL-NamedQuery Example-------------------------
Hibernate: select bankbo0_.accno as accno1_, bankbo0_.accname as accname1_, bankbo0_.balance as balance1_ from bank bankbo0_ where bankbo0_.balance>?
Rakesh, 4000.0
CHANDU, 5000.0
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