MariaDB [tmp]> create table a ( c text not null default '', b int  ) engine = innodb;

Query OK, 0 rows affected (0.01 sec)

MariaDB [tmp]> show  columns from a;

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

| Field | Type    | Null | Key | Default | Extra |

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

| c     | text    | NO   |     | ''      |       |

| b     | int(11) | YES  |     | NULL    |       |

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

2 rows in set (0.00 sec)

MariaDB [tmp]> 

MariaDB [tmp]> drop table a;

Query OK, 0 rows affected (0.00 sec)

MariaDB [tmp]> create table a ( c varchar(3) not null default '', b int  ) engine = innodb;

Query OK, 0 rows affected (0.02 sec)

MariaDB [tmp]> show  columns from a;

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

| Field | Type       | Null | Key | Default | Extra |

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

| c     | varchar(3) | NO   |     |         |       |

| b     | int(11)    | YES  |     | NULL    |       |

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

2 rows in set (0.00 sec)

select column_name, column_default from information_schema.columns where table_name = 'a';

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

| column_name | column_default |

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

| c           | ''             |

| b           | NULL           |

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