Database-Add a column of commands to the original table

MySQL adds a column of commands to a table in one place

If you want to add a column to a table that has already been built, you can use the following example:

ALTER TABLE t1 add column addr varchar (a) not null;

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

ALTER TABLE t1 add column addr varchar (NO) null after User1;

Note that the above command means adding addr to the column after User1. If you want to add to the first column, you can use:

ALTER TABLE t1 add column addr varchar (a) not NULL first;

Database-Add a column of commands to the original table (GO)