mybatis中的where多条件查询 sql动态查询

最新推荐文章于 2023-09-02 08:00:00 发布

原创最新推荐文章于 2023-09-02 08:00:00 发布 · 1.6k 阅读

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#mybatis

本文详细解读了如何在Mybatis中使用条件语句构建动态SQL，包括`if`标签的应用，以及一个测试案例展示查询过程。从配置到实际操作，涵盖了查询全查、单条件和多条件组合的场景。

<select id="dongtaiSelect" resultMap="BaseResultMap" parameterType="com.hp.bean.Person">
  select * from person p
    <where>
      <if test="id != null and id != '' ">
          p.id=#{id}
      </if>

      <if test="name != null and name != '' ">
          and p.name=#{name}
      </if>

      <if test="gender != null and gender != '' ">
          and p.gender=#{gender}
      </if>

      <if test="birthday != null and birthday != '' ">
          and p.birthday=#{birthday}
      </if>

      <if test="address != null and address != '' ">
          and p.address=#{address}
      </if>

      <if test="score != null and score != '' ">
          and p.score>#{score}
      </if>
    </where>
</select>

测试类

public class MybatisTest {
    //让你讲一下 mybatis的执行流程
    //导包-配置sqlmapconfig链接数据库-用sqlSessionFactory读取xml文件-建立一个工厂类
    private SqlSession sqlSession;
    @Before//在@Test之前 执行的方法 提取重复的代码
    public void before() throws IOException {
        //加载并读取xml
        String path = "SqlMapConfig.xml";
        InputStream is = Resources.getResourceAsStream(path);
        //sql链接的工厂类
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        sqlSession = sqlSessionFactory.openSession();
        System.out.println("sqlSession = " + sqlSession);
        //sqlSession.close();
    }

        @Test
        public void test15(){
            Person person = new Person();
            //person.setId(14);//select * from person where p.id=? 不传参数就是全查
            person.setGender(2);
            person.setScore(100);
//如果传一个null或者不传默认就是全查   传值就是根据条件查
//List<Person> list = sqlSession.selectList("com.hp.dao.PersonDao.dongtaiSelect",null);
            List<Person> list =         sqlSession.selectList("com.hp.dao.PersonDao.dongtaiSelect", person);
            for (Person person1 : list) {
                System.out.println("person1 = " + person1);
            }
            sqlSession.close();
        }

}