How to combine duplicate values into one with corresponding value separated by hyphens in MySQL?

To combine, use GROUP_CONCAT() function to combine some attributes in two rows into one. As a separator, use hyphens.

Let us first create a table −

mysql> create table DemoTable1386
   -> (
   -> Title varchar(255),
   -> Name varchar(60)
   -> );
Query OK, 0 rows affected (0.67 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable1386 values('Introduction to MySQL','Paul DuBois');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable1386 values('Java in Depth','Khalid Mughal');
Query OK, 1 row affected (0.48 sec)
mysql> insert into DemoTable1386 values('Introduction to MySQL','Russell Dyer');
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable1386 values('Java in Depth','Joshua Bloch');
Query OK, 1 row affected (0.17 sec)

Display all records from the table using select statement −

mysql> select * from DemoTable1386;

This will produce the following output −

+-----------------------+---------------+
| Title                 | Name          |
+-----------------------+---------------+
| Introduction to MySQL | Paul DuBois   |
| Java in Depth         | Khalid Mughal |
| Introduction to MySQL | Russell Dyer  |
| Java in Depth         | Joshua Bloch  |
+-----------------------+---------------+
4 rows in set (0.00 sec)

Following is the query to combine duplicate values −

mysql> select Title,group_concat(Name separator '----') from DemoTable1386
-> group by Title;

This will produce the following output −

+-----------------------+-------------------------------------+
| Title                 | group_concat(Name separator '----') |
+-----------------------+-------------------------------------+
| Introduction to MySQL | Paul DuBois----Russell Dyer         |
| Java in Depth         | Khalid Mughal----Joshua Bloch       |
+-----------------------+-------------------------------------+
2 rows in set (0.00 sec)