FileMaker® Pro 10 Bible

Chapter 15. Maintaining Referential Integrity

IN THIS CHAPTER

Surveying threats to referential integrity

Understanding the importance of relational keys

Working with keys and data types

Bringing data into line with optimal relational design

Automating the removal of redundant data

Considering data integrity in wider contexts

Managing a solution's data dependencies

Referential integrity, an essential concept, lies at the very heart of relational database development. Ideally, the end users of your solutions take referential integrity for granted — and you, as developer, place it before many other considerations. I think it's important enough to devote an entire chapter to the topic because I know that without referential integrity, all your beautifully built solutions will crumble and amount to nothing.

Pinpointing Common Causes of Referential Integrity Problems

Referential integrity has many dimensions, the problem of orphaned records foremost among them. Consider, for a moment, an invoicing system where you have an invoice table and a line items table storing the items for each invoice. However, an invoice has been deleted without the corresponding line item records being deleted. Now, when you perform a search, you get a different result when you search in the Invoices table than when you search in the Line Items table. The difference arises because the deleted invoice's items remain in the Line Items table, so they appear there, but no related record exists in the Invoices table, so they ...