如何在mysql中通过逗号分隔的字段在另一张表中查到多条记录

表一结构

-- ----------------------------
-- Table structure for test1
-- ----------------------------
DROP TABLE IF EXISTS `test1`;
CREATE TABLE `test1` (
  `t1_id` int(11) NOT NULL AUTO_INCREMENT,
  `t1_name` varchar(255) DEFAULT NULL,
  `t2_id` varchar(30) DEFAULT NULL,
  PRIMARY KEY (`t1_id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of test1
-- ----------------------------
INSERT INTO `test1` VALUES ('1', 'dj', '1,2');
INSERT INTO `test1` VALUES ('2', 'zf', '2,3');

表二结构

-- ----------------------------
-- Table structure for test2
-- ----------------------------
DROP TABLE IF EXISTS `test2`;
CREATE TABLE `test2` (
  `t2_id` int(11) NOT NULL AUTO_INCREMENT,
  `t2_value` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`t2_id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of test2
-- ----------------------------
INSERT INTO `test2` VALUES ('1', 'value1');
INSERT INTO `test2` VALUES ('2', 'value2');
INSERT INTO `test2` VALUES ('3', 'value3');
INSERT INTO `test2` VALUES ('4', 'value4');

sql语句

select ta.t1_id,GROUP_CONCAT(ta.t2_value) from
(
    select t1.t1_id,t1.t1_name,t1.t2_id t2id,t2.t2_id,t2.t2_value,FIND_IN_SET(t2.t2_id,t1.t2_id) tt from test1 t1,test2 t2
) ta
where tt>0
GROUP BY ta.t1_id

结果

1   value1,value2
2   value2,value3