Question

我在MS sql服务器中有主表和子表。我在子表中有一个外键引用。但是仍然没有建立联系，值变成了空。

所以我有“学生”表和“ AcademicInfo”表。以下是其专栏。

学生-> [学生编号，姓名，姓氏，城市]

AcademicInfo-> [Id，StudentIdentity，主题，年份]

现在，我的外键在子表中，该表是带有父Student的StudentId列的AcademicInfo（StudentIdentity）。

我的案例是一对一的关系，因为一个学生只能有一个科目（仅出于锻炼目的）

AcademicInfo.java

package com.luv2code.hibernate.demo.entity;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name="AcademicInfo")
public class AcademicInfo {
	
	public AcademicInfo()
	{}


	public AcademicInfo(String subject, Integer year) {		
		Subject = subject;
		Year = year;
	}


	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY) 
	@Column(name="Id")
	private int Id;
	
	

	@Column(name="Subject")
	public String Subject;
	
	@Column(name="Year")
	public Integer Year;

	public int getId() {
		return Id;
	}

	public void setId(int id) {
		Id = id;
	}

	public String getSubject() {
		return Subject;
	}

	public void setSubject(String subject) {
		Subject = subject;
	}

	public Integer getYear() {
		return Year;
	}

	public void setYear(Integer year) {
		Year = year;
	}


	@Override
	public String toString() {
		return "AcademicInfo [Id=" + Id  + ", Subject=" + Subject + ", Year=" + Year + "]";
	}
	
	
	@OneToOne(cascade= {CascadeType.PERSIST,CascadeType.MERGE,CascadeType.DETACH,CascadeType.REFRESH})
	@JoinColumn(name="StudentIdentity")
	private Student studentInfo;

	public Student getStudentInfo() {
		return studentInfo;
	}


	public void setStudentInfo(Student studentInfo) {
		this.studentInfo = studentInfo;
	}

	
}

Student.java

package com.luv2code.hibernate.demo.entity;
import javax.persistence.*;


@Entity
@Table(name="StudentDetails")
public class Student {
	
	public Student()
	{}

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY) 
	@Column(name="StudentID")
	private int StudentID;
	

	
	@Column(name="Name")
	public String StudentName;
	

	@Column(name="Surname")
	public String Surname;
	
	@Column(name="City")
	public String City;
	
	public int getStudentID() {
		return StudentID;
	}

	
	
	
	public void setStudentID(int studentID) {
		StudentID = studentID;
	}

	public String getName() {
		return StudentName;
	}

	public void setName(String name) {
		StudentName = name;
	}

	public String getSurname() {
		return Surname;
	}

	public void setSurname(String surname) {
		Surname = surname;
	}

	public String getCity() {
		return City;
	}

	public void setCity(String city) {
		City = city;
	}

	

	public Student(String name, String surname, String city) {		
		StudentName = name;
		Surname = surname;
		City = city;
	}

	
	
	@Override
	public String toString() {
		return "Student [StudentID=" + StudentID + ", StudentName=" + StudentName + ", Surname=" + Surname + ", City="
				+ City + "]";
	}

	@OneToOne(mappedBy="studentInfo",cascade= {CascadeType.PERSIST,CascadeType.MERGE,CascadeType.DETACH,CascadeType.REFRESH})
	private AcademicInfo academicDetails;

	public AcademicInfo getAcademicDetails() {
		return academicDetails;
	}


	public void setAcademicDetails(AcademicInfo academicDetails) {
		this.academicDetails = academicDetails;
	}

	
	


	
	
	
}

主应用

package com.luv2code.hibernate.newDemo;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

import com.luv2code.hibernate.demo.entity.AcademicInfo;
import com.luv2code.hibernate.demo.entity.Student;

public class CreateStudentDemo {

	public static void main(String[] args) {

		SessionFactory factory = new Configuration()
				                 .configure("hibernate.cfg.xml")
				                 .addAnnotatedClass(AcademicInfo.class)
				                 .addAnnotatedClass(Student.class)
				                 .buildSessionFactory();
		
		Session session = factory.getCurrentSession();
		
		session.beginTransaction();
		
		Student theStudent1 = new Student("Andy","test","NY");
		AcademicInfo stuAcademics = new AcademicInfo("OS", 2001);
				
		theStudent1.setAcademicDetails(stuAcademics);
		
		System.out.println(theStudent1);

		session.save(stuAcademics);
		
		session.getTransaction().commit();
		
		
		try {
			
		}
		finally {
			factory.close();
		}
			
		
	}

}

以下是“ hibernate.cfg.xml”

<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <!-- JDBC Database connection settings -->
        <property name="connection.driver_class">com.microsoft.sqlserver.jdbc.SQLServerDriver</property>
        <property name="connection.url">jdbc:sqlserver://localhost:1433;databaseName=India;integratedSecurity=true</property>
        <property name="connection.username">sa</property>
        <property name="connection.password">Temp1234</property>

        <!-- JDBC connection pool settings ... using built-in test pool -->
        <property name="connection.pool_size">100</property>

        <!-- Select our SQL dialect -->
        <property name="dialect">org.hibernate.dialect.SQLServer2008Dialect</property>

        <!-- Echo the SQL to stdout -->
        <property name="show_sql">true</property>

		<!-- Set the current session context -->
		<property name="current_session_context_class">thread</property>
 
    </session-factory>

</hibernate-configuration>

它引发如下错误：无法将值NULL插入表“ dbo.AcademicInfo”的“ StudentIdentity”列中；列不允许为空。 INSERT失败。
如果我已经声明了关联，为什么不自动插入studentId？

Answer 1

我使用以下链接进行更改

https://www.callicoder.com/hibernate-spring-boot-jpa-one-to-one-mapping-example/

现在抛出以下错误？

Exception in thread "main" org.hibernate.TransientPropertyValueException: Not-null property references a transient value - transient instance must be saved before current operation : com.luv2code.hibernate.demo.entity.AcademicInfo.studentInfo -> com.luv2code.hibernate.demo.entity.Student

我做对了吗？是否将studentId自动保存在StudentIdentity列中？

外键值未保存在子表的休眠状态

1 个答案: