iBATIS - 删除操作

本章介绍如何使用 iBATIS 从表中删除记录。

我们在 MySQL 中有以下 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)
);

假设此表有两个记录，如下所示 -

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，您无需修改 Employee.java 文件。让我们使其保持在上一个章节中的状态。

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

要使用 iBATIS 定义 SQL 映射语句，我们会在 Employee.xml 中添加 <delete> 标记，并且在这个标记定义内，我们将定义一个会用于 IbatisDelete.java 文件中，用于对数据库执行 SQL DELETE 查询的“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

此文件具有应用程序级别逻辑，用于从 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

以下是在编译和运行上述软件的步骤。确保在继续进行编译和执行之前，已经正确设置了 PATH 和 CLASSPATH。

如上所示创建 Employee.xml。
如上所示创建 Employee.java 并编译它。
如上所示创建 IbatisDelete.java 并编译它。
执行 IbatisDelete 二进制文件以运行该程序。

您将获得以下结果，并且 ID = 1 的记录将从 EMPLOYEE 表中删除，并且会读取其余记录。

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

打印页面