Question

I am creating a program that stores customer payments in a database.

It is possible to pay multiple times for one product, but I don’t want to create a separate column for each payment that the customer makes.

I thought about making the number of columns variable by adding a new one after each payment, but this seems like a bad solution to me…

Any suggestions ?

I think the table should look something like this:

ID    ClientID   ProductID   Payment????.....

Answer 1

As in the comments about, you should have a payment table linked to the user tables.

Customer
{
  ID,
  Name etc...

}

Payment
{
   Amount
   CustomerId, (foreign key to customer table)
   ProductId,
   etc...
}

Then to see get payments made by a Customer:

Select * 
From Customer 
Inner join Payment on Customer.Id = Payment.CustomerId
where customer.id == ?