MyBatis知多少（22）MyBatis删除操作

本节从表中使用MyBatis删除记录。

我们已经在MySQL下有EMPLOYEE表：

 CREATE TABLE EMPLOYEE (
    id INT NOT NULL auto_increment,
    first_name VARCHAR(20) default NULL,
    last_name  VARCHAR(20) default NULL,
    salary     INT  default NULL,
    PRIMARY KEY (id)
 );

假设这个表是有两条记录如下：

mysql> select * from EMPLOYEE;
+----+------------+-----------+--------+
| id | first_name | last_name | salary |
+----+------------+-----------+--------+
|  1 | Zara       | Ali       |   5000 |
|  2 | Roma       | Ali       |   3000 |
+----+------------+-----------+--------+
2 row in set (0.00 sec)

Employee POJO 类:

要执行删除操作，就需要修改Employee.java文件。

 public class Employee {
   private int id;
   private String first_name;
   private String last_name;
   private int salary;  

   /* Define constructors for the Employee class. */
   public Employee() {}

   public Employee(String fname, String lname, int salary) {
     this.first_name = fname;
     this.last_name = lname;
     this.salary = salary;
   }

  /* Here are the required method definitions */
   public int getId() {
     return id;
   }
   public void setId(int id) {
     this.id = id;
   }
   public String getFirstName() {
     return first_name;
   }
   public void setFirstName(String fname) {
     this.first_name = fname;
   }
   public String getLastName() {
     return last_name;
   }
   public void setlastName(String lname) {
     this.last_name = lname;
   }
   public int getSalary() {
     return salary;
   }
   public void setSalary(int salary) {
     this.salary = salary;
   }

  } /* End of Employee */

Employee.xml 文件:

要定义使用MyBatis SQL映射语句中，我们将增加<Delete>键标签Employee.xml文件，这个标签定义中，我们会定义将用于在IbatisDelete.java文件执行SQL DELETE查询数据库的“id”。

 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE sqlMap
 PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN"
 "http://ibatis.apache.org/dtd/sql-map-2.dtd">

 <sqlMap namespace="Employee">
 <insert id="insert" parameterClass="Employee">
    INSERT INTO EMPLOYEE(first_name, last_name, salary)
    values (#first_name#, #last_name#, #salary#)

    <selectKey resultClass="int" keyProperty="id">
       select last_insert_id() as id
    </selectKey>

 </insert>

 <select id="getAll" resultClass="Employee">
    SELECT * FROM EMPLOYEE
 </select>

 <update id="update" parameterClass="Employee">
    UPDATE EMPLOYEE
    SET    first_name = #first_name#
    WHERE  id = #id#
 </update>

 <delete id="delete" parameterClass="int">
    DELETE FROM EMPLOYEE
    WHERE  id = #id#
 </delete>

 </sqlMap>

IbatisDelete.java 文件:

文件将应用程序级别的逻辑从Employee表中删除记录：

 import com.ibatis.common.resources.Resources;
 import com.ibatis.sqlmap.client.SqlMapClient;
 import com.ibatis.sqlmap.client.SqlMapClientBuilder;
 import java.io.*;
 import java.sql.SQLException;
 import java.util.*;

 public class IbatisDelete{
   public static void main(String[] args)
    throws IOException,SQLException{
    Reader rd = Resources.getResourceAsReader("SqlMapConfig.xml");
    SqlMapClient smc = SqlMapClientBuilder.buildSqlMapClient(rd);

    /* This would delete one record in Employee table. */
    System.out.println("Going to delete record.....");
    int id = 1;

    smc.delete("Employee.delete", id );
    System.out.println("Record deleted Successfully ");

    System.out.println("Going to read records.....");
    List <Employee> ems = (List<Employee>)
                         smc.queryForList("Employee.getAll", null);
    Employee em = null;
    for (Employee e : ems) {
       System.out.print("  " + e.getId());
       System.out.print("  " + e.getFirstName());
       System.out.print("  " + e.getLastName());
       System.out.print("  " + e.getSalary());
       em = e;
       System.out.println("");
    }    

    System.out.println("Records Read Successfully ");

   }
 }

编译和运行：

下面是步骤来编译并运行上述软件。请确保已在进行的编译和执行之前，适当地设置PATH和CLASSPATH。

• 创建Employee.xml如上所示。

• 创建Employee.java如上图所示，并编译它。

• 创建IbatisDelete.java如上图所示，并编译它。

• 执行IbatisDelete二进制文件来运行程序。

得到以下结果，ID=1将在EMPLOYEE表中被删除，并读取EMPLOYEE表中的一条记录。

Going to delete record.....
Record deleted Successfully
Going to read records.....
  2  Roma  Ali  3000
Records Read Successfully

系列文章：

MyBatis知多少（1）

MyBatis知多少（2）

MyBatis知多少（3）

MyBatis知多少（4）MyBatis的优势

MyBatis知多少（5）业务对象模型

MyBatis知多少（6）表现层与业务逻辑层

MyBatis知多少（7）持久层

MyBatis知多少（8）关系型数据库

MyBatis知多少（9）不同类型的数据库

MyBatis知多少（10）应用程序数据库

MyBatis知多少（11）企业数据库

MyBatis知多少（12）私有数据库

MyBatis知多少（13）MyBatis如何解决数据库的常见问题

MyBatis知多少（14）分散的数据库系统

MyBatis知多少（15）数据模型

MyBatis知多少（16）MyBatis映射

MyBatis知多少（17）MyBatis和JDBC

MyBatis知多少（18）MyBatis系统

MyBatis知多少（19）MyBatis操作

MyBatis知多少（20）MyBatis读取操作

MyBatis知多少（21）更新操作