Hibernate的查询大致分为以下三种场景，
1. HQL查询-hibernate Query Language(多表查询,但不复杂时使用)
2. Criteria查询(单表条件查询)
3. 原生SQL查询(复杂的业务查询)
接下来解释三种使用方法:
1.HQL查询-hibernate Query Language(多表查询,但不复杂时使用) Hibernate独家查询语言,属于面向对象的查询语言，HQL语言中不会出现SQL中的表和列，HQL使用的都是JavaBean的类名和属性名。
1.HQL基本查询
(1)查询所有的基本语句
@Test
// HQL查询所有数据
public void fun1() {
// 1 获得session
Session session = HibernateUtil.openSession();
// 2.书写HQL语句
String hql = "from cn.qlq.domain.Customer";// from 类名全路径
// 3.根据hql创建查询对象
Query query = session.createQuery(hql);
// 4.根据查询对象获取查询结果
List<Customer> customers = query.list();
System.out.println(customers);
}
结果:
Hibernate:
select
customer0_.cust_id as cust_id1_0_,
customer0_.cust_name as cust_nam2_0_,
customer0_.cust_source as cust_sou3_0_,
customer0_.cust_industry as cust_ind4_0_,
customer0_.cust_level as cust_lev5_0_,
customer0_.cust_linkman as cust_lin6_0_,
customer0_.cust_phone as cust_pho7_0_,
customer0_.cust_mobile as cust_mob8_0_
from
cst_customer customer0_
[Customer [cust_id=1, cust_name=XXXXXXXXXX], Customer [cust_id=2, cust_name=联想]]
改进:如果整个项目中只有一个类的名字可以省略包路径，也就是可以只写类名:
@Test
// HQL查询所有数据
public void fun1() {
// 1 获得session
Session session = HibernateUtil.openSession();
// 2.书写HQL语句
// String hql = "from cn.qlq.domain.Customer";// from 类名全路径
String hql = "from Customer";// 如果整个项目中只有这一个类名可以直接写名字
// 3.根据hql创建查询对象
Query query = session.createQuery(hql);
// 4.根据查询对象获取查询结果
List<Customer> customers = query.list();
System.out.println(customers);
}
(2)根据主键查询单个
@Test
// HQL查询单个数据
public void fun2() {
// 1 获得session
Session session = HibernateUtil.openSession();
// 2.书写HQL语句
// String hql = "from cn.qlq.domain.Customer";// from 类名全路径
String hql = "from Customer where cust_id = 1";// where后面是Customer的属性名称而不是列名
// 3.根据hql创建查询对象
Query query = session.createQuery(hql);
// 4.根据查询对象获取查询结果
Customer customer = (Customer) query.uniqueResult();
System.out.println(customer);
}
2.HQL条件查询:
(1)?占位符查询
类似于JDBC的占位符，只是hibernate的?下标从0开始，而JDBC的下标从1开始，基本上所有的编程索引都从0开始，唯独JDBC从1开始。。。。
@Test
// HQL的?占位符查询
public void fun3() {
// 1 获得session
Session session = HibernateUtil.openSession();
// 2.书写HQL语句
// String hql = "from cn.qlq.domain.Customer";// from 类名全路径
String hql = "from Customer where cust_id = ?";// 如果整个项目中只有这一个类名可以直接写名字
// 3.根据hql创建查询对象
Query query = session.createQuery(hql);
// query.setLong(0, 1l);//类似于JDBC的占位符，只是JDBC的占位符下标从0开始，hibernate从1开始
query.setParameter(0, 1l);//这种写法不用管类型
// 4.根据查询对象获取查询结果
Customer customer = (Customer) query.uniqueResult();
System.out.println(customer);
}
(2)命令占位符 ：name格式的查询，固定格式，name随便起，习惯性的起做和条件名字一样
@Test
// HQL的命令占位符查询
public void fun4() {
// 1 获得session
Session session = HibernateUtil.openSession();
// 2.书写HQL语句
// String hql = "from cn.qlq.domain.Customer";// from 类名全路径
String hql = "from Customer where cust_id = :cust_id";// :cust_id的名字随便起，只不过习惯性的起做一样
// 3.根据hql创建查询对象
Query query = session.createQuery(hql);
// query.setLong(0, 1l);//类似于JDBC的占位符，只是JDBC的占位符下标从0开始，hibernate从1开始
query.setParameter("cust_id",1l);
// 4.根据查询对象获取查询结果
Customer customer = (Customer) query.uniqueResult();
System.out.println(customer);
}
3.HQL排序与分页查询
分页查询类似于mysql的limit关键字，limit start，pageSize。。。。。。
@Test
// HQL分页查询
public void fun5() {
// 1 获得session
Session session = HibernateUtils.openSession();
// 2.书写HQL语句
// String hql = "from cn.qlq.domain.Customer";// from 类名全路径
String hql = "from Customer order by cust_id desc";// :cust_id的名字随便起，只不过习惯性的起做一样
// 3.根据hql创建查询对象
Query query = session.createQuery(hql);
/**
* 类似于 limit start,pageSize;
* 假设页大小是2
* 页号 起始值 页大小
* 1 0 2
* 2 2 2
*/
//例如取第二页数据
query.setFirstResult(2);
query.setMaxResults(2);
// 4.根据查询对象获取查询结果
List<Customer> customers = query.list();
System.out.println(customers);
}
结果:
Hibernate:
select
customer0_.cust_id as cust_id1_0_,
customer0_.cust_name as cust_nam2_0_,
customer0_.cust_source as cust_sou3_0_,
customer0_.cust_industry as cust_ind4_0_,
customer0_.cust_level as cust_lev5_0_,
customer0_.cust_linkman as cust_lin6_0_,
customer0_.cust_phone as cust_pho7_0_,
customer0_.cust_mobile as cust_mob8_0_
from
cst_customer customer0_ limit ?,
?
[Customer [cust_id=2, cust_name=新增数据], Customer [cust_id=1, cust_name=程序员111]]
2.Criteria查询(单表条件查询)
criteria查询相比于上面的HQL查询要简单的多。
1.基本查询---查询所有
@Test
// 查询所有
public void test1() {
// 1 获得session
Session session = HibernateUtils.openSession();
// 2.創建criteria进行查询
Criteria criteria = session.createCriteria(Customer.class);
List<Customer> list = criteria.list();
System.out.println(list);
}
结果:
[Customer [cust_id=1, cust_name=程序员111], Customer [cust_id=2, cust_name=新增数据], Customer [cust_id=3, cust_name=测试名称222], Customer [cust_id=4, cust_name=测试名称222]]
2. 条件查询单个:
@Test
// 根据ID查询单个,条件查询
public void test2() {
// 1 获得session
Session session = HibernateUtils.openSession();
// 2.創建criteria进行查询
Criteria criteria = session.createCriteria(Customer.class);
criteria.add(Restrictions.eq("cust_id", 1l));
Customer customer = (Customer) criteria.uniqueResult();
System.out.println(customer);
}
结果:
Customer [cust_id=1, cust_name=程序员111]
条件列表:
3.分页查询:
@Test
// 分页查询
public void test3() {
// 1 获得session
Session session = HibernateUtils.openSession();
// 2.創建criteria进行查询
Criteria criteria = session.createCriteria(Customer.class);
/**
* 类似于 limit start,pageSize;
* 假设页大小是2
* 页号 起始值 页大小
* 1 0 2
* 2 2 2
*/
criteria.setFirstResult(2);
criteria.setMaxResults(2);
List<Customer> list = criteria.list();
System.out.println(list);
}
结果:
[Customer [cust_id=3, cust_name=测试名称222], Customer [cust_id=4, cust_name=测试名称222]]
4.排序分组使用
@Test
// 排序和分组
public void test5() {
// 1 获得session
Session session = HibernateUtils.openSession();
// 2.排序
Criteria criteria = session.createCriteria(Customer.class);
criteria.addOrder(Order.desc("cust_id"));
List<Customer> list = criteria.list();
System.out.println(list);
System.out.println();
// 2.分组
Criteria criteria1 = session.createCriteria(Customer.class);
criteria1.setProjection(Projections.groupProperty("cust_name"));
List<Customer> list1 = criteria1.list();
System.out.println(list1);
}
结果：
[Customer [cust_id=4, cust_name=测试名称222], Customer [cust_id=3, cust_name=测试名称222], Customer [cust_id=2, cust_name=新增数据], Customer [cust_id=1, cust_name=程序员111]]
[新增数据, 测试名称222, 程序员111]
5.聚集函数查询总数
@Test
// 查询总数（聚集函数的使用）
public void test4() {
// 1 获得session
Session session = HibernateUtils.openSession();
// 2.聚集函数查询总数
Criteria criteria = session.createCriteria(Customer.class);
criteria.setProjection(Projections.rowCount());
Long count = (Long) criteria.uniqueResult();
System.out.println(count);
// 3.聚集函数查询总数第二种方法
Criteria criteria1 = session.createCriteria(Customer.class);
criteria1.setProjection(Projections.count("cust_id"));
Long count1 = (Long) criteria.uniqueResult();
System.out.println(count1);
// 4.聚集函数查询几个不同的姓名
Criteria criteria2 = session.createCriteria(Customer.class);
criteria2.setProjection(Projections.countDistinct("cust_name"));
Long count2 = (Long) criteria2.uniqueResult();
System.out.println(count2);
}
结果:
4
4
3
3.Hibernate种的原生SQL查询(用于处理一些复杂的业务逻辑)
1.基本查询
1.查询结构是数组集合
@Test
// 基本查询--返回数组list
public void test1() {
// 1.获取与线程绑定的session
Session session = HibernateUtils.getCurrentSession();
// 2.开启事务
Transaction tx = session.beginTransaction();
String sql = "select * from cst_customer";// 3.构造Query对象进行查询
SQLQuery sqlQuery = session.createSQLQuery(sql);
List<Object[]> list = sqlQuery.list();
for (Object[] o : list) {
System.out.println(Arrays.toString(o));
}
// 提交事务
tx.commit();
}
结果
[1, 程序员111, null, null, null, null, null, null]
[2, 新增数据, null, null, null, null, null, null]
[3, 测试名称222, null, null, null, null, null, null]
[4, 测试名称222, null, null, null, null, null, null]
2.查询结果是对象集合(重要)
@Test
// 基本查询--返回对象list
public void test2() {
// 1.获取与线程绑定的session
Session session = HibernateUtils.getCurrentSession();
// 2.开启事务
Transaction tx = session.beginTransaction();
String sql = "select * from cst_customer";// 3.构造Query对象进行查询
SQLQuery sqlQuery = session.createSQLQuery(sql);
sqlQuery.addEntity(Customer.class);
List<Customer> list = sqlQuery.list();
System.out.println(list);
// 提交事务
tx.commit();
}
结果
[Customer [cust_id=1, cust_name=程序员111], Customer [cust_id=2, cust_name=新增数据], Customer [cust_id=3, cust_name=测试名称222], Customer [cust_id=4, cust_name=测试名称222]]
2.条件查询
@Test
// 基本查询--返回对象list
public void test3() {
// 1.获取与线程绑定的session
Session session = HibernateUtils.getCurrentSession();
// 2.开启事务
Transaction tx = session.beginTransaction();
String sql = "select * from cst_customer where cust_id=?";// 3.构造Query对象进行查询
SQLQuery sqlQuery = session.createSQLQuery(sql);
sqlQuery.addEntity(Customer.class);
sqlQuery.setParameter(0, 1l);
Customer cus = (Customer) sqlQuery.uniqueResult();
System.out.println(cus);
// 提交事务
tx.commit();
}
结果
Customer [cust_id=1, cust_name=程序员111]
3.聚集函数查询总数
@Test
// 基本查询--查询总数
public void test4() {
// 1.获取与线程绑定的session
Session session = HibernateUtils.getCurrentSession();
// 2.开启事务
Transaction tx = session.beginTransaction();
String sql = "select count(*) from cst_customer";// 3.构造Query对象进行查询
SQLQuery sqlQuery = session.createSQLQuery(sql);
BigInteger bg = (BigInteger) sqlQuery.uniqueResult();
System.out.println(bg);
// 提交事务
tx.commit();
}
结果
4
4.排序与分页综合查询
@Test
// 基本查询--分页查询
public void test5() {
// 1.获取与线程绑定的session
Session session = HibernateUtils.getCurrentSession();
// 2.开启事务
Transaction tx = session.beginTransaction();
//按cust_id降序排序
String sql = "select * from cst_customer order by cust_id desc limit ?,?";// 3.构造Query对象进行查询
SQLQuery sqlQuery = session.createSQLQuery(sql);
sqlQuery.addEntity(Customer.class);
/**
* 分页查询 取第二页，页大小是二
*/
sqlQuery.setParameter(0, 2);
sqlQuery.setParameter(1, 2);
List<Customer> list = sqlQuery.list();
System.out.println(list);
// 提交事务
tx.commit();
}
结果
[Customer [cust_id=2, cust_name=新增数据], Customer [cust_id=1, cust_name=程序员111]]
4.原生SQL映射为MAP:
@Test
/**
* 原生SQL查询(SQLQuery映射查询结果为map)
*/
public void fun6(){
Session session = HibernateUtil.openSession();
Transaction tx = session.beginTransaction(); String sql = "select * from cst_customer";
SQLQuery sqlQuery = session.createSQLQuery(sql);
sqlQuery.setResultTransformer(Transformers.ALIAS_TO_ENTITY_MAP);
System.out.println(sqlQuery.list()); tx.commit();
session.close();
}
结果:
[{cust_phone=null, cust_name=测试名称1, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=7}, {cust_phone=null, cust_name=测试名称2, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=8}, {cust_phone=null, cust_name=测试名称3, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=9}, {cust_phone=null, cust_name=测试名称4, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=10}, {cust_phone=null, cust_name=测试名称5, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=11}, {cust_phone=null, cust_name=测试名称6, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=12}, {cust_phone=null, cust_name=测试名称7, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=13}]
5.hibernate原生SQL进行插入操作
@Test
// 原生SQL执行插入操作
public void test6() {
// 1.获取与线程绑定的session
Session session = HibernateUtils.getCurrentSession();
// 2.开启事务
Transaction tx = session.beginTransaction();
String sql = "insert into user values('xxxx','李四',23)";;// 3.构造Query对象进行插入
SQLQuery sqlQuery = session.createSQLQuery(sql);
sqlQuery.executeUpdate();
// 提交事务
tx.commit();
}