i have an other problem

i have 2 tables on the db
one is id_names which has 2 rows: id(key) , and name
and the other one is employees_info which also have id(key) , and some more rows

i did a data relation between id_names and employees_info which are related with the id

now my problem is this:
when i update the id on the id_names table it doesn't update the id on the employees_info table

so, how can i do it?
thanks