mysql默认值？
In my database, is it standard to leave most fields with default value "none"? For example a user id, a post title, category, or tags.
在我的数据库中，保留大多数默认值为“none”的字段是否标准？ 例如，用户ID，帖子标题，类别或标签。 p> div>
For required fields such as username or password, you should set NOT NULL. For other optional fields you can set it to NULL. For numbers, it is almost always a good idea to set default value to zero 0 .
I'll answer your question as I best understand it.
For User_id, it is common to set its default value to auto_increment. SQL will automatically fill this in when you create a new record.
Text fields will default to null, although when you create the table you can set a DEFAULT such as ' ', 'cat' or anything else you like.