MySQL adds a column of commands at a certain position in the table

If you want to add a column to a created table, you can use:

Alter table T1 add column ADDR varchar (20) not null;

This statement adds an ADDR column to the existing table T1, which is located in the last column of the table. If you want to add a column in the specified column, you can use:

Alter table T1 add column ADDR varchar (20) not null after user1;

Note: The above command means to add the ADDR column to the end of the user1 column. If you want to add the column to the first column, you can use:

Alter table T1 add column ADDR varchar (20) not null first;