Create Table User (Username Varchar (16) Not Null Primary Key, Passwd Char (16) Not Null, Admin Enum ('NO', 'YES') Not Null; this table is correct.
Create Table User (Username Varchar (16) Not Null Primary Key, Passwd Char (16) Not Null, All Enum ('NO', 'YES') NOT NULL);
This table is wrong because all cannot be used as a column name.
The column type is unsigned and the input data is 0, which will be automatically reset to 1. If 10 data of 0-9 is continuously entered, the Duplicate error will appear. As shown in the following table. Create Table County (Countyid Tinyint Unsigned Not Null Auto_Increment Primary Key, Countyname Char (20) Not null;
