Mybatis映射文件-增删改查

刺骨的言语ヽ痛彻心扉 2022-05-13 13:34 267阅读 0赞

以接口编程开始，首先建立一个增删改查的我接口类

publlic interface EmployeeMapper{
    public Employee getEmpById(Interger id);//查询
    public void addEmpt(Employee employee);//增加
    public void deleteEmptById(Integer id);//删除
    public void updateEmpt(Employee employee);//更改
    
    }

在 EmployeeMapper.xml中添加方法

<?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="com.guigu.mybatis.EmployeeMapper> 
       <!--namespace为命名空间， id为唯一标识，resultType返回值类型用类全路径,#{id}从传递的参数中取出id 值>
        <select id="getEmpById" resultType="com.guigu.mybatis.Employee"> 
         select  id,last_name lastName,email,gender from  tbl_employee where id = #{id}
      </select>
       </mapper>
       //mybatis支持自增主键的获取
    <insert id="addEmpt" parameterType="com.guigu.mybatis.Employee" **useGeneratedKeys="true" keyProperty="id">**//使用自增主键获取,获取的主键值给id
            insert into  tbl_employee (last_name,email,gender) values(#{lastName},#{email},#{gender})
           </insert>
    <update id="updateEmpt">
    update tbl_employee set last_name=#{lastName},email=#{email},gender=#{gender} where id=#{id}
    </update>
    <delete id="deleteEmptById">
    delete from tbl_employee where id=#{id}
    </delete>

写测试类

@Test
        public  void test(){
        String reource="Mybatis-config.xml";
        InputStream inputStream=Resource.getResourceAsStream(reource);
        SqlSessionFactory sqlSessionFactory =new SqlSessionFactoryBuilder().build(inputStream);
        **//获取的 sqlSession openSession()不会自动提交数据*需要手动提交
       // sqlSession openSession(ture)不用手动提交了
        SqlSession sqlSession=sqlSessionFactory .openSession();
        try {EmployeeMapper employeeMapper=sqlSession.getMapper(EmployeeMapper.class);
        employeeMapper.getEmpById(1);
        Employee employee=new Employee(null,"lili","123@qq","1");
        Employee employee1=new Employee(1,"wli","123@qq","0");
        employeeMapper.addEmpt(employee);
        employeeMapper.updateEmpt(employee1);
        employeeMapper.deleteEmptById(2);
        **sqlSession.commit();**
        }finally{sqlSession.close();}
        }

Oracle不支持自增，Oracle使用序列来模拟自增  
，每次插入的数据的主键是从序列中拿到的值，如何获取整个值

<insert id="addEmpt" databaseId="oracle">
    <selectKey keyProperty="id" order ="before" resultType="Interger"/>//先查询主键,把值给id,在插入之前运行
    select employees_seq.nextval from dual 
    </selectKey>
    insert into employees(Employee_id,last_name,email,gender)
    values(#{id},#{lastName},#{email},#{gender})
    </insert >