9.0.2以下的:alter table tab add (col_c number(2,0) );update tab set col_c =col_a删除foreign key
alter table tab drop constraint constrain_name;
alter table tab drop column col_a;
添加约束。
alter table tab add constraint constraint_name foreigner key (col_c) references ....
alter table tab drop constraint constrain_name;
alter table tab drop column col_a;
添加约束。
alter table tab add constraint constraint_name foreigner key (col_c) references ....
可以
alter table tab rename column col_a to col_c;