MySql 8 concatenating a string

In the table table_c stored an a database MySql version 8.0.17 I have these rows

-- ----------------------------
-- Table structure for table_c
-- ----------------------------
DROP TABLE IF EXISTS `table_c`;
CREATE TABLE `table_c`  (
  `contents` longtext DEFAULT NULL,
  `ID_contents` int(11) DEFAULT NULL,
  `ID` int(11) NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`ID`) USING BTREE
) ENGINE = InnoDB;

-- ----------------------------
-- Records of table_c
-- ----------------------------
INSERT INTO `table_c` VALUES ('- Par 1', 1, 1);
INSERT INTO `table_c` VALUES ('Content 1.1', 1, 2);
INSERT INTO `table_c` VALUES ('1 Veni, vidi, vici', 1, 3);
INSERT INTO `table_c` VALUES ('2 Carpe diem', 1, 4);
INSERT INTO `table_c` VALUES ('3 Ubi maior minor cessat', 1, 5);
INSERT INTO `table_c` VALUES ('- Par 2', 2, 6);
INSERT INTO `table_c` VALUES ('Content 2.1', 2, 7);
INSERT INTO `table_c` VALUES ('1 Condicio sine qua non', 2, 8);
INSERT INTO `table_c` VALUES ('2 Carthago delenda est', 2, 9);
INSERT INTO `table_c` VALUES ('3 Inter sidera versor', 2, 10);

I need this return

+-------------+-------------------------------------------------------------------------+
| id_contents | Contents                                                                |
+-------------+-------------------------------------------------------------------------+
|           1 | 1 Veni, vidi, vici;2 Carpe diem;3 Ubi maior minor cessat                |
|           2 | 1 Condicio sine qua non;2 Carthago delenda est;3 Inter sidera versor    |
+-------------+-------------------------------------------------------------------------+

I have tried SQL Fiddle without success…

Any help would greatly appreciate… Thank you…

Answer

You have to add only GROUP BY clause like following

GROUP BY  id_contents

DEMO