I am building a software for a repair shop

I am using free tables

I've created a table clients and a table devices
In the table clients I have a field called "code"
and in the table devices I have a field called "id"

I created a relation between the fields code and id
This relation was created in the dataenvironment

I have a problem:

When a client is deleted their devices stays still in
the table devices

I mean; if I delete client number #2 the devices with id # 2
o the table devices will still be there.

When a new client is added to the record # 2 of the table clients,
he will get the devices of the table devices with id # 2

How can I solve this problem ?