1.HQL:(Hibernate Query Language) 是面向对象的查询语言
1.实体查询
public void testQueryAllDept(){
String hql="from Employee";
//hql="from com.sh.Entity";
Query query=session.createQuery(hql);
List<Employee> list= query.list();
//...
}
2.有条件的 实体查询
public void testQueryAllDept(){
String hql="from Deptas model where mode.deptName='人事部' ";
//hql="from com.sh.Entity";
Query query=session.createQuery(hql);
List<Employee> list= query.list();
//...
}
public void testQueryAllDept(){
String hql="from Deptas model where mode.deptName like '%部%' ";
//hql="from com.sh.Entity";
Query query=session.createQuery(hql);
List<Employee> list= query.list();
//...
}
public void testQueryDeptByGt(){
String hql="from Dept model where model.createDate> '2012-03-10'";
Query query=session.createQuery(hql);
List<Employee> list= query.list();
}
3.HQL 中的各种运算符
| 运算符类型 | HQL运算符 | 含义 |
| 比较运算 | = | 等于 |
| <> | 不等于 | |
| > | 大于 | |
| >= | 大于等于 | |
| <= | 小于等于 | |
| < | 小于 | |
| is null | 为空 | |
| is not null | 不为空 | |
| 范围运算 | in | 等于列表中的某一值 |
| not in | 不等于列表中的任意一个值 | |
| between p1 and p2 | 大于等于值1 且 小于等于值2 | |
| not between p1 and p2 | 小于值1 或者 大于 值2 | |
| 字符串模式匹配 | like | 字符串模式匹配 |
| 逻辑运算 | and | 与 |
| or | 或 | |
| not | 非 |
3.更新 删除
public void testModifyDate(){
Transaction tr=session.beginTransaction();
Dept detp=(Dept)session.get(Detp.class,new Integer(6));
detp.seteCreateDate("2000-03-10");
tr.commit();
}
// delete 删除
public void testDelDeptByHql(){
Transaction tr=session.beginTransaction();
String hql="delete Dept as model where model.deptId=6";
Query query=session.createQuery(hql);
query.executeUpdate();
tr.commit();
}
4.属性查询
public void testQueryDeptName(){
String hql="select model.deptName from Dept as model";
Query query=session.createQuery(hql);
List<String> deptNameList=query.list();
//...
}
public void testQueryDeptName(){
String hql="select model.deptName,model.createDate from Dept as model";
Query query=session.createQuery(hql);
List<Object[]> prsList=query.list();
for(){
}
//...
}
//采用对象进行 保存 查询的字段(要添加 对应字段的构造方法)
public void testQueryDeptName(){
String hql="select new Dapt(model.deptName,model.createDate) from Dept as model";
Query query=session.createQuery(hql);
List<Dept> deptList=query.list();
for(Dept d:deptList){
d.setDeptName("test");
session.saveOrUpdate(dept);
}
//...
}
//如果采用对象 保存上面查询出来的对象 如果对其进行更新的操作 是不会成功的
public void testSaveDept(){
Transction tr=session.beginTransactino();
String hql="select new Dept(model.deptName,model.createDate) from Dept as model";
Query query=session.createQuery();
List<Dept> deptList=query.list();
for(Dept dept:deptList){
System.out.println(dept.deptName);
dept.setDetpName("test");
session.saveOrUpdate(dept);
}
tr.commit();
// 最后 根本就没有更新 而是 在数据库中 插入 新的记录
}
5.使用函数
6.分组 与 排序
//排序
public void testQueryOrderBy(){
String hql="from Dept as mode order by model.createDate,model.deptName desc";
Query query=session.createQuery();
List<Dept> deptList=query.list();
for(){}
//
}
//分组 并且 使用 having 筛选
public void testQueryGroupBy(){
String hql="select count(model),model.deptName from Dept as model group by model.deptName having count(model)>1";
Query query=session.createQuery();
List<Object[]> list=query.list();
//...
}
7.查询单个对象
public void testQueryUn(){
String hql="select model.deptName from Dept as model where model.deptId=2";
Query query=session.createQuery(hql);
query.setMaxResults(1);
String deptName=(String)query.uniqueResult();
System.out.println(deptNamae);
}
8.绑定参数
释义:Hibernate中也采用了preparedStatement作为底层数据库的的访问方式,与之对应的SQL语句 可以重用preparedStatement对象, 首先会预编译,然后缓存起来,提高性能.
1.使用 ":"加参数名 绑定参数
public void testQueryByParamsName(){
//使用 ":参数名" 来传递参数
String hql="from Dept as model where
odel.deptName=:deptName and model.createDate=:createDate";
Query query=session.createQuery(hql);
query.setString("deptName","test");
query.setString("ceateDate","2000-02-10");
List<Dept> deptList=query.list();
for(){}
//...
}
2.使用 "?" 按照位置来绑定参数
public void testQueryByParamsID(){
String hql="from Dept as model where model.deptName=? and model.createDate=?";
Query query=session.createQuery(hql);
query.setString(0,"test");
query.setString(1,"2000-02-02");
List<Dept> list=query.list();
for(){}
//..
}
3.采用setEntity() 将参数和一个持久化对象进行绑定
public void testQueryByDept(){
Dept dept=(Dept)Session.get(Dept.clas,new Integer(2));
String hql="select Employee as model where model.dept=?"
Query query=session.createQuery(hql);
query.setEntity(0,dept);
List<Employee> empList=query.list();
for(){}
//..
}
4.setParameter() 用于绑定任意类型的参数
public void testQueryBySetParams(){
String hql="from Dept as model where model.deptName=?";
Query query=session.createQuery(hql);
query.setParameter(0,"test");
List<Dept> deptList=query.list();
for(){}
//..
}
5.setProperties() 将一个参数名 于一个对象的属性值绑定
public void testQueryBySetPro(){
Dept deptNew=new Dept();
deptNew.setDeptName("test");
String hql="from Dept as model where model.deptName=:deptName";
Query query=session.createQuery();
query.setProperties(deptNew);
List<Dept> deptList=query.list();
for(){
}
//..
}
10. 联合查询
inner join
public void testQueryInnerJoin(){
String hql="from Dept as model inner join model1.employees as model2";
Query query=session.createQuery(hql);
List<Object[]> objList=query.list();
for(Object[] obj:objList){
Dept dept=(Dept)obj[0];
Employee emp=(Employee)obj[1];
System.out.println("xxxx");
}
}
left join
right join
public void testQueryRightJoin(){
String hql="from Dept as model right join model1.employees as model2";
Query query=session.createQuery(hql);
List<Object[]> objList=query.list();
for(Object[] obj:objList){
Dept dept=(Dept)obj[0];
Employee emp=(Employee)obj[1]; //有可能为空 所以需要判断
if(dept!=null){
System.out.println(dept.getDeptName());
}else{
System.out.println(null);
}
System.out.println("dd"+emp.getEmployeeName());
}
}
11.子查询
public void testQueryChild(){
String hql="from Dept as model where (select count(*) from model.employee) >2";
Query query=session.createQuery(hql);
List<Dept> objList=query.list();
for(){}
//..
}
12 Criteria 查询
释义:通过面向对象的设计将数据查询条件封装在一个对象
//无条件
public void testQueryDept(){
Criteria criteria=session.createCriteria(Dept.class);
List<Dept> deptList=criteria.list();
for(){}
//..
}
//添加条件
public void testQueryDeptByName(){
Criteria criteria=session.createCriteria(Dept.class);
criteria.add(Expression.eq("deptName", "人事部"));
List<Dept> deptList=criteria.list();
for(){}
//..
}
SQL语法查询机制
| 方法 | 描述 |
| Expression.eq | 对应sql中的field =value |
| Expression.gt | 对应sql中的field>value |
| Expression.ge | 对应sql中的field>=value |
| Expression.lt | 对应sql中的field<value |
| Expression.le | 对应sql中的field<=value |
| Expression.between | 对应sql中的between |
| Expression.like | 对应 like |
| Expression.in | 对应 in |
| Expression.eqProperty | 用于比较两个属性之间的值,对应的Sql条件中field=field |
| Expression.gtProperty | 用于比较两个属性之间的值,对Sqlfiled>field |
| Expression.geProperty | 用于比较两个属性之间的值,对应sql field>=field |
| Expression.ltProperty | 用于比较两个属性之间的值,对应field<field |
| Expression.leProperty | 用于比较 两个属性之间的值,对应field<=field |
Hibernate3中采用Restrictions类代替Expression
public void testQueryDeptByNameRe(){
Criteria criteria=session.createCriteria(Dept.class);
criteria.add(Restrictions.eq("deptName", "人事部"));
List<Dept> deptList=criteria.list();
for(){}
//..
}
Criteria中限定返回的行数
public void testQueryDept(){
Criteria criteria=session.createCriteria(Dept.class);
criteria.setFirstResult(2);
criteria.setMaxResults(2);
List<Dept> deptList=criteria.list();
for(){}
//..
}
Criteria排序
public void testQueryDept(){
Criteria criteria=session.createCriteria(Dept.class);
criteria.addOrder(Order.asc("createDate"));
List<Dept> deptList=criteria.list();
for(){}
//..
}
转载：http://www.cnblogs.com/jifeng/archive/2013/03/03/2941181.html