java - 如何使用HQL从实体中获取数据？

Question

我正在使用 HQL 从数据库中获取数据我遇到了 sql 语法异常请检查我的代码

Emp.java

@Entity

@Table(name="TBL_STD_EMP")
public class Emp 
{

@Id 
@GeneratedValue
   @Column(name = "id")
   private int id;

   @Column(name = "first_name")
   private String firstName;

   @Column(name = "last_name")
   private String lastName;

   @Column(name="SALARY")
   private int salary;  
   @Temporal(TemporalType.DATE)
   private Date joinDate;
   @ElementCollection
   @JoinTable(name="EMP_ADDRESS" ,joinColumns=@JoinColumn(name="USER_ID"))
   java.util.Collection <Address> address= new java.util.ArrayList<Address>();
     //setter and geeter methods

} 我的可嵌入类

@Embeddable
public class Address {
@Column(name="DOOR_NO")
int doorNO;

public int getDoorNO() {
    return doorNO;
}
public void setDoorNO(int doorNO) {
    this.doorNO = doorNO;
}
public String getStreetName() {
    return streetName;
}
public void setStreetName(String streetName) {
    this.streetName = streetName;
}
public String getCountryName() {
    return countryName;
}
public void setCountryName(String countryName) {
    this.countryName = countryName;
}
@Column(name="STREET_NAME")
String streetName;
@Column(name="COUNTY_NAME")
String countryName;

} 我的主课 包 com.hib.busness;

 import java.util.Date; 
 import java.util.List;

 import org.hibernate.HibernateException;
 import org.hibernate.Query;
 import org.hibernate.Session;
 import org.hibernate.SessionFactory;
 import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

 import com.hib.dto.Address;
 import com.hib.dto.EMP;

 public class MainClass {

/**
 * @param args
 */
private static SessionFactory factory;

public static void main(String[] args) {
    // TODO Auto-generated method stub

    try {
        factory = new Configuration().configure().buildSessionFactory();

    } catch (Throwable ex) {
        System.err.println("Failed to create sessionFactory object." + ex);
        throw new ExceptionInInitializerError(ex);
    }

    Transaction tx = null;
    Integer employeeID = null;
    Session session = factory.openSession();
    try {
        tx = session.beginTransaction();
        EMP employee = new EMP();
        employee.setFirstName("bhanu1");
        employee.setLastName("prasad");
        employee.setSalary(30000);
        employee.setJoinDate(new Date());
        employee.setDescription("Working as ProductEngineer");
        Address address = new Address();
        address.setCountryName("India");
        address.setDoorNO(1);
        address.setStreetName("mainStreet");
        Address address1 = new Address();
        address1.setCountryName("India1");
        address1.setDoorNO(2);
        address1.setStreetName("mainStreet1");
        employee.getAddress().add(address);
        employee.getAddress().add(address1);

        employeeID = (Integer) session.save(employee);
        tx.commit();
        tx = session.beginTransaction();
        String hql = "FROM EMP where  lastName='prasad' and doorNO=2";
        Query query = session.createQuery(hql);
        List results = query.list();
        System.out.println(results);
    } catch (HibernateException e) {
        if (tx != null)
            tx.rollback();
        e.printStackTrace();
    } finally {
        session.close();
    }

}

 }

有人帮我解决了 SQLSyntex 异常。

Answer 1

在 HQL 中，您可以使用点表示法导航实体的字段。在 Emp 和 Address 之间建立关联后，您可以在 HQL 语句中使用它。由于 doorNO 字段位于 Address 实体上，您应该通过 address 访问它。

尝试:

String hql = "FROM EMP e where e.lastName='prasad' and e.address.doorNO=2";