hibernate demo查询语句

dept.java

public class dept {
private int deptid;
private String deptname;
private Set<employee> emps= new HashSet<employee>();
public int getDeptid() {
    return deptid;
}
public void setDeptid(int deptid) {
    this.deptid = deptid;
}
public String getDeptname() {
    return deptname;
}
public void setDeptname(String deptname) {
    this.deptname = deptname;
}
public Set<employee> getEmps() {
    return emps;
}
public void setEmps(Set<employee> emps) {
    this.emps = emps;
}

}

dept.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    
    
    
<hibernate-mapping  package="cn.itcast.aquery" >  
    <class name="dept"  table="t_dept">
    <id name="deptid" >
    <generator class="native"></generator>
    
    </id>
    <property name="deptname" length="20"/>   
//该处 length=20 如果不加引号，myeclipse会提示无法读取xml ， 错误信息 ！该处错误较为难找！
    
    <set name="emps">
    <key column="dept_id"></key>
    <one-to-many  class="employee"/>
    
    </set>
    </class>
    
    </hibernate-mapping>

employee.java

public class employee {
private int empid;
private String empname;
private double salary;
private dept dept;
public int getEmpid() {
    return empid;
}
public void setEmpid(int empid) {
    this.empid = empid;
}
public String getEmpname() {
    return empname;
}
public void setEmpname(String empname) {
    this.empname = empname;
}
public double getSalary() {
    return salary;
}
public void setSalary(double salary) {
    this.salary = salary;
}
public dept getDept() {
    return dept;
}
public void setDept(dept dept) {
    this.dept = dept;
}

}

employee.hbm.xml

<hibernate-mapping  package="cn.itcast.aquery" >  
    <class name="employee"  table="t_employ">
    <id name="empid" >
    <generator class="native"></generator>
    
    </id>
    <property name="empname"  length="20" />
    
     
     <property name="salary" type="double"></property>
     <many-to-one name="dept" column="dept_id "  class="dept"></many-to-one>
    


    </class>
    </hibernate-mapping>

app.java

public class app {
    private static SessionFactory  sf;
    static {
        sf=new Configuration().configure().addClass(dept.class).addClass(employee.class).buildSessionFactory();
    }
    @Test
    public void get_load() throws Exception{
        Session  session=sf.openSession();
        session.beginTransaction();
        dept dept=(dept)session.get(dept.class,2);
        System.out.println(dept.getDeptname());
        System.out.println(dept.getEmps());
        session.getTransaction().commit();
        session.close();

    }
    }

2.HQL查询

dept.hbm.xml   

<hibernate-mapping  package="cn.itcast.aquery"      auto-import="true">  

app.java

Query q=session.createQuery("from dept");
System.out.println(q.list());

如果auto-import ="false'      Query q=session.createQuery("from cn.itcast.aquery.dept");   该处要写完整包名

===============================

3.将查询语句放入配置文件中

public class app {
private static SessionFactory sf;
static {
sf=new Configuration().configure().addClass(dept.class).addClass(employee.class).buildSessionFactory();
}
@Test
public void get_load() throws Exception{
Session session=sf.openSession();
session.beginTransaction();
/*    dept dept=(dept)session.get(dept.class,2);
System.out.println(dept.getDeptname());
System.out.println(dept.getEmps());*/


//Query q=session.createQuery("select d.deptid,d.deptname from dept d");


Query q = session.getNamedQuery("getalldept");   //配置文件中 配置名称  getalldept


/*    q.setParameter("myid", 0);
q.setParameter("name", "财务部");*/


q.setParameter(0,7);
System.out.println(q.list());

session.getTransaction().commit();
session.close();

}
}

dept.hbm.xml

<hibernate-mapping  package="cn.itcast.aquery" auto-import="true">  
    <class name="dept"  table="t_dept">
    <id name="deptid" >
    <generator class="native"></generator>
    
    </id>
    <property name="deptname" length="20"/>
    
    <set name="emps">
    <key column="dept_id"></key>
    <one-to-many  class="employee"/>
    
    </set>
    </class>
    
    
    <query name="getalldept">
    <!--  from dept d where deptid=:myid or deptname=:name-->
        <![CDATA[
            from dept d where deptid < ?
        ]]>
    </query>
    
    </hibernate-mapping>

4。 Criteria 查询，
@Test
public void criteria() {

Session session = sf.openSession();
session.beginTransaction();

Criteria criteria = session.createCriteria(Employee.class);
// 构建条件
criteria.add(Restrictions.eq("empId", 12));
//    criteria.add(Restrictions.idEq(12)); // 主键查询

System.out.println(criteria.list());


session.getTransaction().commit();
session.close();
}

5。    SQLQuery， 本地SQL查询
// 不能跨数据库平台： 如果该了数据库，sql语句有肯能要改。
@Test
public void sql() {

Session session = sf.openSession();
session.beginTransaction();

SQLQuery q = session.createSQLQuery("SELECT * FROM t_Dept limit 5;")
.addEntity(Dept.class); // 也可以自动封装
System.out.println(q.list());

session.getTransaction().commit();
session.close();
}

}