oracle - update table column/constraints

Hi,

I am going to change the order of a tables columns in database 'A' and re-apply the contraints so it is the same as database 'B'.

i get the current order from 'A' with

desc table_name;

so i will use

update table_name set x = y;

what i need to know is:

how do i find out what constraints are in place on database 'B' and apply them to database 'A'.

is there anything else i need to check e.g. index's or recompiling any packages.

thanks