更新&&删除
语法格式:(HQL)
update | delete from?
1>在from子句中,from关键字是可选的,即完全可以不写from关键字
2>在from子句中,只能有一个类名,可以在该类名后指定别名
3>不能在批量HQL语句中使用连接,显示或者隐式的都不行,但可以在where子句中使用子查询
4>整个where子句是可选的,where子句的语法sql语句中where子句的语法完全相同
5>Query.executeUpdate()方法返回一个整型值,该值是受此操作影响的记录数量,由于hibernate的底层操作实际上是由JDBC完成的,因此,如果有批量update或delete操作被转换成多条update或delete语句,(关联或者继承映射),该方法只能返回最后一条sql语句影响的记录行数,不是所有的记录行数,需要注意;
一,批量更新(两种方式)
1,使用Hibernate直接进行批量更新
(1)方式1:(Hibernate的HQL直接支持update/delete的批量更新语法)
package com.anlw.util;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
public class SessionUtil {
Configuration conf = null;
ServiceRegistry st = null;
SessionFactory sf = null;
Session sess = null;
Transaction tx = null;
public void HIbernateTest() {
conf = new Configuration().configure();
st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
sf = conf.buildSessionFactory(st);
try {
sess = sf.openSession();
tx = sess.beginTransaction();
//在HQL查询中使用update进行批量更新,下面的的语句是HQL语句,不是sql语句
Query query = sess.createQuery("update Student set name = 'www'");
query.executeUpdate();
tx.commit();
} catch (Exception e) {
if (tx != null) {
tx.rollback();
}
} finally {
sess.close();
sf.close();
}
}
public static void main(String[] args) {
new SessionUtil().HIbernateTest();
}
}
(2)方式2:(强烈不推荐)
package com.anlw.util;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import org.hibernate.CacheMode;
import org.hibernate.Query;
import org.hibernate.ScrollMode;
import org.hibernate.ScrollableResults;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.jdbc.Work;
import org.hibernate.service.ServiceRegistry;
import com.anlw.entity.Student;
public class SessionUtil {
Configuration conf = null;
ServiceRegistry st = null;
SessionFactory sf = null;
Session sess = null;
Transaction tx = null;
public void HIbernateTest() {
conf = new Configuration().configure();
st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
sf = conf.buildSessionFactory(st);
try {
sess = sf.openSession();
tx = sess.beginTransaction();
//查询表中的所有数据
ScrollableResults student = sess.createQuery("from Student")
.setCacheMode(CacheMode.IGNORE)
.scroll(ScrollMode.FORWARD_ONLY);
int count = 0;
while(student.next()){
Student s = (Student)student.get(0);
s.setName("haha");
if(++count%3 == 0){
sess.flush();
sess.clear();
}
}
tx.commit();
} catch (Exception e) {
if (tx != null) {
tx.rollback();
}
} finally {
sess.close();
sf.close();
}
}
public static void main(String[] args) {
new SessionUtil().HIbernateTest();
}
}
通过这种方式,虽然可以执行批量更新,但效果非常不好,执行效率不高,需要先执行数据查询,然后再执行数据更新,而且这种更新将是逐行更新,即每更新一行记录,都要执行一条update语句,性能非常低;2,绕过Hibernate,调用JDBC API
(1)方式1:
package com.anlw.util;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.jdbc.Work;
import org.hibernate.service.ServiceRegistry;
public class SessionUtil {
Configuration conf = null;
ServiceRegistry st = null;
SessionFactory sf = null;
Session sess = null;
Transaction tx = null;
public void HIbernateTest() {
conf = new Configuration().configure();
st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
sf = conf.buildSessionFactory(st);
try {
sess = sf.openSession();
tx = sess.beginTransaction();
//执行Work对象指定的操作,即调用Work对象的execute()方法
//Session会把当前使用的数据库连接传给execute()方法
sess.doWork(new Work() {
@Override
public void execute(Connection arg0) throws SQLException {//需要注意的是,不需要调用close()方法关闭这个连接
String sql = "update student set name = 'oracle'";
//创建一个Satement对象
Statement st = arg0.createStatement();
//调用JDBC的update进行批量更新
st.executeUpdate(sql);
}
});
tx.commit();
} catch (Exception e) {
if (tx != null) {
tx.rollback();
}
} finally {
sess.close();
sf.close();
}
}
public static void main(String[] args) {
new SessionUtil().HIbernateTest();
}
}
(2)方式2:
package com.anlw.util;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.jdbc.Work;
import org.hibernate.service.ServiceRegistry;
public class SessionUtil {
Configuration conf = null;
ServiceRegistry st = null;
SessionFactory sf = null;
Session sess = null;
Transaction tx = null;
public void HIbernateTest() {
conf = new Configuration().configure();
st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
sf = conf.buildSessionFactory(st);
try {
sess = sf.openSession();
tx = sess.beginTransaction();
//执行Work对象指定的操作,即调用Work对象的execute()方法
//Session会把当前使用的数据库连接传给execute()方法
sess.doWork(new Work() {
@Override
public void execute(Connection arg0) throws SQLException {//需要注意的是,不需要调用close()方法关闭这个连接
String sql = "update student set name = ? where name=?";
PreparedStatement ps = arg0.prepareStatement(sql);
for(int i=0;i<10;i++){
ps.setString(1,"tom");
ps.setString(2, "oracle");
ps.addBatch();
}
ps.executeBatch();
}
});
tx.commit();
} catch (Exception e) {
if (tx != null) {
tx.rollback();
}
} finally {
sess.close();
sf.close();
}
}
public static void main(String[] args) {
new SessionUtil().HIbernateTest();
}
}
二,批量删除(两种方式)
1,使用Hibernate直接进行批量删除
(1)方式1:(Hibernate的HQL直接支持update/delete的批量更新语法)
package com.anlw.util;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
public class SessionUtil {
Configuration conf = null;
ServiceRegistry st = null;
SessionFactory sf = null;
Session sess = null;
Transaction tx = null;
public void HIbernateTest() {
conf = new Configuration().configure();
st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
sf = conf.buildSessionFactory(st);
try {
sess = sf.openSession();
tx = sess.beginTransaction();
//在HQL查询中使用delete进行批量删除,下面的的语句是HQL语句,不是sql
Query query = sess.createQuery("delete Student");//也可以是delete from,from关键字是可选的,可以不要,加条件的时候可以指定类的别名
query.executeUpdate();
tx.commit();
} catch (Exception e) {
if (tx != null) {
tx.rollback();
}
} finally {
sess.close();
sf.close();
}
}
public static void main(String[] args) {
new SessionUtil().HIbernateTest();
}
}
(2)方式2:(强烈不推荐)
package com.anlw.util;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import org.hibernate.CacheMode;
import org.hibernate.Query;
import org.hibernate.ScrollMode;
import org.hibernate.ScrollableResults;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.jdbc.Work;
import org.hibernate.service.ServiceRegistry;
import com.anlw.entity.Student;
public class SessionUtil {
Configuration conf = null;
ServiceRegistry st = null;
SessionFactory sf = null;
Session sess = null;
Transaction tx = null;
public void HIbernateTest() {
conf = new Configuration().configure();
st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
sf = conf.buildSessionFactory(st);
try {
sess = sf.openSession();
tx = sess.beginTransaction();
//查询表中的所有数据
ScrollableResults student = sess.createQuery("from Student")
.setCacheMode(CacheMode.IGNORE)
.scroll(ScrollMode.FORWARD_ONLY);
int count = 0;
while(student.next()){
Student s = (Student)student.get(0);
sess.delete(s);
}
tx.commit();
} catch (Exception e) {
if (tx != null) {
tx.rollback();
}
} finally {
sess.close();
sf.close();
}
}
public static void main(String[] args) {
new SessionUtil().HIbernateTest();
}
}
通过这种方式,虽然可以执行批量删除,但效果非常不好,执行效率不高,需要先执行数据查询,然后再执行数据删除,而且这种删除将是逐行删除,即每删除一行记录,都要执行一条delete语句,性能非常低;2,绕过Hibernate,调用JDBC API
(1)方式1:
package com.anlw.util;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.jdbc.Work;
import org.hibernate.service.ServiceRegistry;
import com.anlw.entity.Student;
public class SessionUtil {
Configuration conf = null;
ServiceRegistry st = null;
SessionFactory sf = null;
Session sess = null;
Transaction tx = null;
public void HIbernateTest() {
conf = new Configuration().configure();
st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
sf = conf.buildSessionFactory(st);
try {
sess = sf.openSession();
tx = sess.beginTransaction();
sess.doWork(new Work() {
@Override
public void execute(Connection arg0) throws SQLException {
String sql = "delete from student where age > 5"; //mysql中删除语句不能省略from
Statement st = arg0.createStatement();
st.executeUpdate(sql);
}
});
tx.commit();
} catch (Exception e) {
if (tx != null) {
tx.rollback();
}
} finally {
sess.close();
sf.close();
}
}
public static void main(String[] args) {
new SessionUtil().HIbernateTest();
}
}
2)方式2:
package com.anlw.util;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.jdbc.Work;
import org.hibernate.service.ServiceRegistry;
import com.anlw.entity.Student;
public class SessionUtil {
Configuration conf = null;
ServiceRegistry st = null;
SessionFactory sf = null;
Session sess = null;
Transaction tx = null;
public void HIbernateTest() {
conf = new Configuration().configure();
st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
sf = conf.buildSessionFactory(st);
try {
sess = sf.openSession();
tx = sess.beginTransaction();
sess.doWork(new Work() {
@Override
public void execute(Connection arg0) throws SQLException {
String sql = "delete from student where age = ?"; //mysql中删除语句不能省略from
PreparedStatement ps = arg0.prepareStatement(sql);
for(int i=0;i<10;i++){
if(i%2 == 0){
ps.setInt(1, i);
ps.addBatch();
}
ps.executeBatch();
}
}
});
tx.commit();
} catch (Exception e) {
if (tx != null) {
tx.rollback();
}
} finally {
sess.close();
sf.close();
}
}
public static void main(String[] args) {
new SessionUtil().HIbernateTest();
}
}