Can I Import an updated structure into a MySQL table without losing its current content?

Question

We use MySQL tables to which we add new fields from time to time as our product evolves. I\'m looking for a way to export the structure of the table from one copy of the db, to

Answer 1

for your case, it might just need to perform an update

alter table B add column x varchar(255);
alter table B add column y varchar(255);
alter table B add column z varchar(255);

update A,B 
set 
  B.x=A.x,
  B.y=A.y,
  B.z=A.z
where A.id=B.id; <-- a key that exist on both tables