How to create a field that if data is selected in one table from parent table in a child table it is not available for other child tables.
For example in a CD rent shop there are tables of costumers, CD'S, Loan, Return, Reserve.
Now a costumer wants to reserve a CD and the data from CD table is selected in reserve table. Then how to make it possible that this reserved CD is not available for loan to other costumers.
For example in a CD rent shop there are tables of costumers, CD'S, Loan, Return, Reserve.
Now a costumer wants to reserve a CD and the data from CD table is selected in reserve table. Then how to make it possible that this reserved CD is not available for loan to other costumers.