create table asd(name int check(name=1), age int(1) primary key);
create table qwe(mane int, gae int(1) references asd(age));
alter table qwe
add constraint chk check(mane>2);
show create table qwe;
alter table qwe drop constraint chk;
alter table asd
modify column name int;
show create table asd;
show create table qwe;