Hibernate相关的查询 --Hibernate框架基础
接着上一篇博文：Hibernate第一个程序(最基础的增删改查) --Hibernate本例是对Hibernate查询的扩展，使用HQL语句查询
/**
* HQL添加预先需要保存的测试数据
*/
@Test
public void test_01() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
Student student1 = new Student("貂蝉", 24, 99);
Student student2 = new Student("王昭君", 22, 93);
Student student3 = new Student("杨玉环", 28, 94);
Student student4 = new Student("李师师", 26, 95);
Student student5 = new Student("苏小小", 20, 96);
Student student6 = new Student("李师师", 25, 96);
Student student7 = new Student("唐伯虎", 21, 91);
Student student8 = new Student("祝枝山", 21, 92);
session.save(student1);
session.save(student2);
session.save(student3);
session.save(student4);
session.save(student5);
session.save(student6);
session.save(student7);
session.save(student8);
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
session.getTransaction().rollback();
e.printStackTrace();
}
}
/**
* 使用HQL语句查询信息并且通过升序排列
*/
@Test
public void test_02() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String hql = "from Student order by tscore asc";
List<Student> list = session.createQuery(hql).list();
for (Student student : list) {
System.out.println(student);
}
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* 使用SQL语句查询学生信息并且通过升序排列（对比HQL可忽略）
*/
@Test
public void testSQL_01() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String sql = "select *from t_student order by tscore asc";
List<Student> list = session.createSQLQuery(sql).addEntity(Student.class).list();
for (Student student : list) {
System.out.println(student);
}
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* HQL动态参数绑定查询(占位符)
*/
@Test
public void test_04() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String hql = "from Student where age>? and score<?";
List<Student> list = session.createQuery(hql).setInteger(0, 25).setDouble(1, 97).list();
for (Student student : list) {
System.out.println(student);
}
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* HQL动态参数绑定查询別名的方式
*/
@Test
public void testQuery_HQL_04() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String hql = "from Student where age>:myage and score<:myscore";
List<Student> list = session.createQuery(hql)
.setParameter("myage", 25).setParameter("myscore", 97.0)// 必須是97.0
.list();
for (Student student : list) {
System.out.println(student);
}
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* HQL分页查询
*/
@Test
public void test_05() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String hql = "from Student";
List<Student> list =session.createQuery(hql)
.setFirstResult(1)
.setMaxResults(3)
.list();
for (Student student : list) {
System.out.println(student);
}
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* SQL分页查询（对比,忽略即可）
*/
@Test
public void testSql_06() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String sql = "select *from t_student limit ?,?";
List<Student> list =session.createSQLQuery(sql)
.addEntity(Student.class)
.setInteger(0, 1)//从第5条数据开始
.setInteger(1, 3)
.list();
for (Student student : list) {
System.out.println(student);
}
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* HQL模糊查询
*/
@Test
public void testQuery_SQL_07() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String hql = "from Student where tname like :myname";
List<Student> list =session.createQuery(hql)
.setString("myname", "%王%")
.list();
for (Student student : list) {
System.out.println(student);
}
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* HQL唯一性查询
*/
@Test
public void testQuery_SQL_08() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String hql = "from Student where tid = :myid";
Student student =(Student) session.createQuery(hql)
.setInteger("myid", 1)
.uniqueResult();
System.out.println(student);
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* 聚合函数查询
*/
@Test
public void testQuery_HQL_06() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String hql = "SELECT COUNT(*) from Student";
Long count = (Long) session.createQuery(hql).uniqueResult();
System.out.println(count);// 输出结果有多少条数据
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* 投影查询
*/
@Test
public void testQuery_HQL04() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String hql = "select new Student(name,age) from Student";// 将查询到的字段通过构造方法封装到对象，然后保存在list中
List<Student> list = session.createQuery(hql).list();
for (Student student : list) {
System.out.println(student);// 只查询到name、age信息，其他则为默认
}
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* HQL分组查询 ：查每个年龄段的第一个人
*/
@Test
public void testQuery_HQL05() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String hql = "from Student group by age";
List<Student> list = session.createQuery(hql).list();
for (Student student : list) {
System.out.println(student);
}
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* HQL分组查询：查询有几个年龄段
*/
@Test
public void testQuery_HQL06() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String hql = "select age from Student group by age";
List<Integer> list = session.createQuery(hql).list();
System.out.println(list);
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
/**
* HQL分组查询：查询多于1人的年龄段
*/
@Test
public void testQuery_HQL07() {
Session session = HbnUtils.getSession();
try {
session.beginTransaction();
String hql = "select age from Student group by age having count(age) > 1";
List<Integer> list = session.createQuery(hql).list();
System.out.println(list);
session.getTransaction().commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
session.getTransaction().rollback();
}
}
