Mybatis映射文件动态SQL语句-02

foreach

UserMapper.xml

<?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.hao.mapper.UserMapper">
   <select id="findByCondition" parameterType="user" resultType="user">
       select * from user
       <where>
           <if test="id!=0">
               and id=#{id}
           </if>
           <if test="username!=null">
               and username=#{username}
           </if>
           <if test="password!=null">
               and password=#{password}
           </if>
       </where>
   </select>
    <select id="findByIds" parameterType="list" resultType="user">
        select * from user
        <where>
            <foreach collection="list" open="id in(" close=")" item="id" separator=",">
                #{id}
            </foreach>
        </where>
    </select>
</mapper>

测试

 @Test
    public void test1() throws IOException {
        InputStream stream = Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSession sqlSession = new SqlSessionFactoryBuilder().build(stream).openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
       List<Integer> ids=new ArrayList<>();
       ids.add(1);
       ids.add(2);
        List<User> byIds = mapper.findByIds(ids);
        System.out.println(byIds);
    }

观看打印的日志

-collection 表示要做foreach循环的对象
- item 表示集合中每一个元素或者该集合的对象,支持对象点属性的方式获取属性。
- index 表示循环的下标,从0开始
- open 表示以什么开始
- separator 表示每次进行迭代之间以什么符号作为分隔符
- close表示以什么结束