关于动态SQL另外一个常用的操作就是需要对一个集合进行遍历,通常发生在构建IN条件语句时:

1.mapper.xml

    <select id="selectEmployeeIn" resultType="org.fkit.domain.Employee">
        SELECT * FROM tb_employee WHERE ID IN
        <foreach item="item" index="index" collection="list" open="(" separator="," close=")">
            #{item}
         </foreach>
    </select>

2.mapper.java

List<Employee> selectEmployeeIn(List<Integer> ids);

3.controller

    @GetMapping("/mysql/DynamicSQL/foreach")
    public void dynamicSQLForeach()
    {
        //获得SqlSession实例
        SqlSession sqlSession = FKSqlSessionFactory.getSqlSession();
        //获得Mapper接口代理对象
        EmployeeMapper em = sqlSession.getMapper(EmployeeMapper.class);
        //创建List
        List ids = new ArrayList<Integer>();
        ids.add(1);
        ids.add(3);
        //获取查询结果
        List<Employee> list = em.selectEmployeeIn(ids);
        list.forEach(one -> System.out.println(one.getName()));
    }

4.输出