create table t1 (grp int, a bigint unsigned, c char(10) , d char(10) not null);

insert into t1 values (1,1,NULL,"a");

insert into t1 values (1,10,"b","a");

insert into t1 values (1,11,"c","a");

insert into t1 values (2,2,"c","a");

insert into t1 values (2,3,"b","b");

insert into t1 values (3,4,"E","a");

insert into t1 values (3,5,"C","b");

insert into t1 values (3,6,"D","c");

insert into t1 values (3,7,"E","c");

MariaDB [test]> select grp,group_concat(c) from t1 group by grp;

+------+-----------------+

| grp  | group_concat(c) |

+------+-----------------+

|    1 | b,c             |

|    2 | c,b             |

|    3 | E,C,D,E         |

+------+-----------------+

3 rows in set (0.003 sec)

MariaDB [test]> select grp,group_concat(c limit 1,1 ) from t1 group by grp;

+------+----------------------------+

| grp  | group_concat(c limit 1,1 ) |

+------+----------------------------+

|    1 | c                          |

|    2 | b                          |

|    3 | C                          |

+------+----------------------------+

3 rows in set (0.003 sec)

MariaDB [test]> create view v1 as select grp,group_concat(c limit 1,1 ) from t1 group by grp;

Query OK, 0 rows affected (0.003 sec)

MariaDB [test]> select * from v1;

+------+----------------------------+

| grp  | group_concat(c limit 1,1 ) |

+------+----------------------------+

|    1 | b,c                        |

|    2 | c,b                        |

|    3 | E,C,D,E                    |

+------+----------------------------+

3 rows in set (0.006 sec)