MySQL之FIND_IN_SET()的用法及说明

FIND_IN_SET(str,strlist)

# 创建表
CREATE TABLE IF NOT EXISTS tb_test1(
	`id` INT(11) NOT NULL auto_increment,
    `name` varchar(255) NOT NULL COMMENT '名字',
    `type` varchar(255) NOT NULL COMMENT '类型: 1表示金卡；2表示银卡；3表示铜卡',
    PRIMARY KEY  (`id`)
)ENGINE = INNODB DEFAULT CHARSET = utf8 COMMENT = 'FIND_IN_SET使用';

# 新增数据
INSERT INTO tb_test1(name,type) VALUES('edg','1,2,3');
INSERT INTO tb_test1(name,type) VALUES('rng','2,3');
INSERT INTO tb_test1(name,type) VALUES('ig','1,3');

# 查询
SELECT * FROM tb_test1 WHERE FIND_IN_SET('1',type); # 返回type中包含1的记录

CREATE TABLE IF NOT EXISTS dept(
	`id` INT(11) NOT NULL auto_increment,
    `name` varchar(255) NOT NULL COMMENT '部门名字',
    `user_ids` text DEFAULT NULL COMMENT '部门人员',
     PRIMARY KEY  (`id`)
)ENGINE = INNODB DEFAULT CHARSET = utf8 COMMENT = '部门表';

<resultMap id="ResultMap" type="com.test.entity.dept" >
     <id column="id" property="id" jdbcType="INTEGER" />
     <result column="name" property="name" jdbcType="VARCHAR" />
     <result column="user_ids" property="userIds" jdbcType="VARCHAR" />
     <association property="Users" resultMap="Usesr_map" /> // 在实体类中有List<User> Users
</resultMap>

<sql id="User_Column_List" >
    user.id user_id, user.name user_name
</sql>
    
<resultMap id="Usesr_map" type="com.test.entity.User">
	<id column="user_id" property="id" jdbcType="INTEGER" />
    <result column="user_name" property="name" jdbcType="VARCHAR" />
</resultMap>


<!-- 只返回user_ids中包含的id的user记录 -->
<select id="selectOne" resultMap="ResultMap" parameterType="INTEGER" >
    SELECT
    e.id id,e.name name,e.user_ids user_ids,
    <include refid="User_Column_List"/>
    FROM dept e
    LEFT JOIN User user ON FIND_IN_SET(user.id,e.user_ids)
    WHERE e.id = #{e.id}
</select>