Hello, I have just started doing database design, and one thing that I am wondering is about table relationships. One to one, one to many, and many to many.
In many cases it seems simple, but if i think about it for a while, tables relationships can use either of these.
For example, you have a customer tables and an address table. I would think one customer can have one and only one address, so it would be a one to one relationship. But the opposite is not the same, as an address can belong to one or many customers (if two or more customers are living in the same house)
How do I classify this relationship? is there an easy way I can make the connection in the future, as many examples seem to be confusing me.
No matter what rules you make, there will always be exceptions. Its how well your database handles those exceptions that matters.
In your example of customer names and addresses, there are other variations as well.
One customer with multiple addresses, each office runs independently.
One customer with multiple addresses billed to head office.
Use statistical analysis of the data before designing the database, and then design so that exceptions are minimized.