Database-detailed explanation of field attributes

Database-detailed explanation of field attributes

Unsigned

• Unsigned integer
• Once declared, the column cannot be declared as a negative number

Zerofill

• 0 padding
• Fill the insufficient digits with 0

Self-increasing

• Automatically +1 on the basis of the previous record (default)
• Usually used to design a unique primary key, it must be an integer type
• The starting value and step length of the primary key can be customized

Not null

• Assuming it is set to not null, if you don't assign a value to it, an error will be reported!
• If it is set to null, the default value is null if not filled in!

default

• Set default

• If you do not specify the value of the column, there will be a default value
  expansion: each table must have the following five fields

• id primary key

• version Optimistic lock

• is_delete pseudo delete

• gmt_create creation time

• gmt_updaye modification time