I am using mysql for a project. When I did 'desc table_name', I see that the tabular output shows the Null of the field is set to No, but then 'Default' is set to NULL. How can a field not have a Null but then default is Null itself?
mysql> desc users; +-----------------+------------------+------+-----+----------------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------------+------------------+------+-----+----------------------------+----------------+ | id | int(10) unsigned | NO | PRI | NULL | auto_increment | | created_at | timestamp | YES | | NULL | | | updated_at | timestamp | YES | | NULL | | | email | varchar(255) | NO | | NULL | | | password | varchar(255) | NO | | NULL | | | remember_token | varchar(100) | YES | | NULL | | | profile_pic | varchar(255) | YES | | img/profile/profilepic.jpg | | | activation_code | varchar(255) | YES | UNI | NULL | | | status_id | int(10) unsigned | NO | MUL | 1 | | | profile_id | int(10) unsigned | YES | MUL | NULL | | +-----------------+------------------+------+-----+----------------------------+----------------+ 10 rows in set (0.00 sec)
This is a perfectly legal combination. It means that when you try to insert a new row and do not explicitly specify this column's value, it would default to null and thus error out. This combination is often used as a way to force you to explicitly assign a value to the column instead of just relying on defaults.