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  MyBatis 更新操作

  • 更新操作

    在上一章中，我们讨论了如何使用MyBatis对表执行读操作。本章说明如何使用表来更新表中的记录。
    我们在MySQL中有以下student表- 
    
CREATE TABLE details.student(
   ID int(10) NOT NULL AUTO_INCREMENT,
   NAME varchar(100) NOT NULL,
   BRANCH varchar(255) NOT NULL,
   PERCENTAGE int(3) NOT NULL,
   PHONE int(11) NOT NULL,
   EMAIL varchar(255) NOT NULL,
   PRIMARY KEY (`ID`)
);
    假设此表具有两个记录，如下所示- 
    
mysql> select * from STUDENT;
+----+----------+--------+------------+-----------+--------------------+
| ID |   NAME   | BRANCH | PERCENTAGE |   PHONE   |      EMAIL         |
+----+----------+--------+------------+-----------+--------------------+
| 1  | Mohammad |   It   |     80     | 984803322 | Mohammad@gmail.com |
| 2  | shyam    |   It   |     75     | 984800000 | shyam@gmail.com    |
+----+----------+--------+------------+-----------+--------------------+

  • Student POJO类

    要执行更新操作，您需要将Student.java文件修改为- 
    
public class Student {

   private int id;
   private String name;
   private String branch;
   private int percentage;
   private int phone;
   private String email;

   public Student(int id, String name,  String branch, int percentage, int phone, String email) {
      super();
      this.id = id;
      this.name = name;
      this.setBranch(branch);
      this.setPercentage(percentage);
      this.phone = phone;
      this.email = email;
   }
        
   public Student() {}

   public int getId() {
      return id;
   }
        
   public void setId(int id) {
      this.id = id;
   }
        
   public String getName() {
      return name;
   }
        
   public void setName(String name) {
      this.name = name;
   }
        
   public int getPhone() {
      return phone;
   }
        
   public void setPhone(int phone) {
      this.phone = phone;
   }
        
   public String getEmail() {
      return email;
   }
        
   public void setEmail(String email) {
      this.email = email;
   }

   public String getBranch() {
      return branch;
   }

   public void setBranch(String branch) {
      this.branch = branch;
   }

   public int getPercentage() {
      return percentage;
   }

   public void setPercentage(int percentage) {
      this.percentage = percentage;
   }
        
   public String toString(){
      StringBuilder sb = new StringBuilder();
                
      sb.append("Id = ").append(id).append(" - ");
      sb.append("Name = ").append(name).append(" - ");
      sb.append("Branch = ").append(branch).append(" - ");
      sb.append("Percentage = ").append(percentage).append(" - ");
      sb.append("Phone = ").append(phone).append(" - ");
      sb.append("Email = ").append(email);
                
      return sb.toString();
   }
        
}

  • Student.xml文件

    要使用MyBatis定义SQL映射语句，我们将在Student.xml中添加<update>标记，并在该标记定义内，我们将定义一个“id”，该ID将在mybatisUpdate.java文件中用于对数据库执行SQL UPDATE查询。 
    
<?xml version = "1.0" encoding = "UTF-8"?>

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
        
<mapper namespace = "Student">    
   <resultMap id = "result" type = "Student">
      <result property = "id" column = "ID"/>
      <result property = "name" column = "NAME"/>
      <result property = "branch" column = "BRANCH"/>
      <result property = "percentage" column = "PERCENTAGE"/>
      <result property = "phone" column = "PHONE"/>
      <result property = "email" column = "EMAIL"/>
   </resultMap>
    
   <select id = "getById" parameterType = "int" resultMap = "result">
      SELECT * FROM STUDENT WHERE ID = #{id};
   </select>
        
   <update id = "update" parameterType = "Student">
      UPDATE STUDENT SET NAME = #{name}, 
         BRANCH = #{branch}, 
         PERCENTAGE = #{percentage}, 
         PHONE = #{phone}, 
         EMAIL = #{email} 
      WHERE ID = #{id};
   </update>
        
</mapper>

  • mybatisUpdate.java文件

    该文件具有应用程序级逻辑，可将记录更新到Student表中- 
    
import java.io.IOException;
import java.io.Reader;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class mybatisUpdate { 

   public static void main(String args[]) throws IOException{
      
      Reader reader = Resources.getResourceAsReader("SqlMapConfig.xml");
      SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);               
      SqlSession session = sqlSessionFactory.openSession();
      
      //select a particular student using id            
      Student student = (Student) session.selectOne("Student.getById", 1);
      System.out.println("Current details of the student are" );
      System.out.println(student.toString());  
      
      //Set new values to the mail and phone number of the student
      student.setEmail("mohamad123@yahoo.com");
      student.setPhone(90000000);
      
      //Update the student record
      session.update("Student.update",student);
      System.out.println("Record updated successfully");   
      session.commit();   
      session.close();    
          
      //verifying the record 
      Student std = (Student) session.selectOne("Student.getById", 1);
      System.out.println("Details of the student after update operation" );
      System.out.println(std.toString());   
      session.commit();   
      session.close();
                        
   }
}

  • 编译并运行

    这是编译和运行mybatisUpdate.java的步骤。在继续进行编译和执行之前，请确保已正确设置了PATH和CLASSPATH。
    • 如上所示创建Student.xml。
    • 如本教程的MYBATIS-配置XML章节中所示，创建SqlMapConfig.xml 。
    • 如上所示创建Student.java并进行编译。
    • 如上所示创建mybatisUpdate.java并进行编译。
    • 执行mybatisUpdate二进制文件以运行程序。
    您将得到以下结果。您可以最初查看特定记录的详细信息，并且该记录将在student表中进行更新，之后，您还可以查看更新后的记录。 
    
Current details of the student are
Id = 1 - Name = Mohammad - Branch = It - Percentage = 80 - Phone = 984802233 - Email = mohammad@gmail.com
Record updated successfully
Details of the student after update operation
Id = 1 - Name = Mohammad - Branch = It - Percentage = 80 - Phone = 90000000 - Email = mohamad123@yahoo.com
    如果检查student表，它将显示以下结果- 
    
mysql> select * from student;
+----+----------+--------+------------+-----------+----------------------+
| ID |  NAME    | BRANCH | PERCENTAGE |  PHONE    |       EMAIL          |
+----+----------+--------+------------+-----------+----------------------+
| 1  | Mohammad |  It    |     80     |  90000000 | mohamad123@yahoo.com |
| 2  | shyam    |  It    |     75     | 984800000 | shyam@gmail.com      |
+----+----------+--------+------------+-----------+----------------------+
2 rows in set (0.00 sec)
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