Mybatis中sql的增删改查的使用

CRUD

1. namespace需要与自己定义的dao下的接口名一致

2. select

   • 在接口中定义查询的抽象方法

         //查询
         List<People> getPeopleList();
     

   • 在mapper.xml文件中添加映射

     <mapper namespace="com.mcwen.dao.PDao">
         <select id="getPeopleList" resultType="com.mcwen.pojo.People">
             select * from mybatis.people
         </select>
     </mapper>
     

   • 写方法测试

     public class PDaoTest {
     
         @Test
         public void test() {
             SqlSession sqlSession = MybatisUtils.getSqlSession();
             //1
             PDao pDao = sqlSession.getMapper(PDao.class);
             List<People> peopleList = pDao.getPeopleList();
             for (People people : peopleList) {
                 System.out.println(people);
             }
         }
     
         @Test
         public void addPeople() {
             SqlSession sqlSession = MybatisUtils.getSqlSession();
             PDao mapper = sqlSession.getMapper(PDao.class);
             int i = mapper.addPeople(new People(7, "libai", 20));
             i = mapper.addPeople(new People(6, "libai", 20));
             if (i > 0) {
                 System.out.println("添加成功");
                 System.out.println(i);
             }
             sqlSession.commit();
             sqlSession.close();
         }
         @Test
         public void delPeople(){
             SqlSession sqlSession = MybatisUtils.getSqlSession();
             PDao mapper = sqlSession.getMapper(PDao.class);
             int i = mapper.delPeople(7);
             System.out.println("删除了"+i);
     
             sqlSession.commit();
             sqlSession.close();
         }
         @Test
         public void uupdatePeople(){
             SqlSession sqlSession = MybatisUtils.getSqlSession();
             PDao mapper = sqlSession.getMapper(PDao.class);
             mapper.updatePeople(new People(6,"xiaoxiao",4));
             sqlSession.commit();
             sqlSession.close();
         }
     }
     

3. insert

4. delect

5. update

   （流程一样）

   public interface PDao {
       //查询
       List<People> getPeopleList();
       //添加
       int addPeople(People people);
       //删除
       int delPeople(int id);
       //修改
       int updatePeople(People people);
   }
   
   

   <?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.mcwen.dao.PDao">
       <select id="getPeopleList" resultType="com.mcwen.pojo.People">
           select * from mybatis.people
       </select>
       <insert id="addPeople" parameterType="com.mcwen.pojo.People">
           insert into mybatis.people(id,username,age)  values(#{id},#{username},#{age});
       </insert>
       <delete id="delPeople" parameterType="int">
           delete
           from mybatis.people
           where id=#{id};
       </delete>
       <update id="updatePeople" parameterType="com.mcwen.pojo.People">
           update mybatis.people
           set  username=#{username},age=#{age}
           where id=#{id};
       </update>
   </mapper>
   

   注意增删改需要提交事务，不然数据库中不会有反应。

   public class PDaoTest {
   
       @Test
       public void test() {
           SqlSession sqlSession = MybatisUtils.getSqlSession();
           //1
           PDao pDao = sqlSession.getMapper(PDao.class);
           List<People> peopleList = pDao.getPeopleList();
           for (People people : peopleList) {
               System.out.println(people);
           }
       }
   
       @Test
       public void addPeople() {
           SqlSession sqlSession = MybatisUtils.getSqlSession();
           PDao mapper = sqlSession.getMapper(PDao.class);
           int i = mapper.addPeople(new People(7, "libai", 20));
           i = mapper.addPeople(new People(6, "libai", 20));
           if (i > 0) {
               System.out.println("添加成功");
               System.out.println(i);
           }
           sqlSession.commit();//提交事物
           sqlSession.close();
       }
       @Test
       public void delPeople(){
           SqlSession sqlSession = MybatisUtils.getSqlSession();
           PDao mapper = sqlSession.getMapper(PDao.class);
           int i = mapper.delPeople(7);
           System.out.println("删除了"+i);
   
           sqlSession.commit();
           sqlSession.close();
       }
       @Test
       public void uupdatePeople(){
           SqlSession sqlSession = MybatisUtils.getSqlSession();
           PDao mapper = sqlSession.getMapper(PDao.class);
           mapper.updatePeople(new People(6,"xiaoxiao",4));
           sqlSession.commit();
           sqlSession.close();
       }
   }