This set entered on 5-17-14.
5.7.14.1
- p 362. TABLE OCCURRENCES. The Relationship Graph does NOT depict tables–it shows:
TABLE OCCURRENCES (TOs), which are just GRAPHICAL REPRESENTATIONS OF THE UNDERLYING TABLE.
- Since the TABLE OCCURRENCES are ONLY Graphic Representations, you can:
make NEW OCCURRENCES of a TABLE WITHOUT DUPLICATING IT (and ALL its data).
- When you have a simple database, you have only ONE Table Occurrence on the GRAPH for each table, but as the database grows:
you’ll need to graph the same table multiple times so you can keep everything straight. You CANNOT think of a TO as a TABLE.
- The purpose for TOs is to:
allow you to connect with a direct line LAYOUTS ( TOs) that may be on opposite ends of the RELATIONSHIP GRAPH and connected only through several other tables.
- Say your DATABASE has an EXPENSES TABLE to record what you buy to service your customers. It also has a LINE ITEMS table to record what you charge your customers for. But these two tables are connected by way of jobs. How is this not IDEAL?
It means you DON’T know which LINE ITEM is actually billing for a particular expense. In other words, when you look at a LINE ITEM, YOU CANNOT TELL WHAT EXPENSE IT IS BILLING FOR.
- For the problem in card #5, you COULD type that information into the LINE ITEMS::DESCRIPTION field, but this does nothing to help FileMaker know how:
these two things are connected.
- How, then, do you solve the issue from card #5?
CRATE A WHOLE NEW RELATIONSHIP, one that DIRECTLY connects EXPENSES and LINE ITEMS. This new RELATIONSHIP lets you use GTRR commands to toggle between EXPENSES and INVOICES (Line Items? 6-3-14), for example.
- The EXPENSES table-LINE ITEMS table RELATIONSHIP is a (O to M, O to O, M to M) :
ONE TO ONE. It is UNUSUAL NOT only because it is a ONE TO ONE, but also because it connects TWO COMPLETELY DIFFERENT TYPES OF DATA.
- However, if you CONNECT EXPENSES and LINE ITEMS in the EXISTING RELATIONSHIP GRAPH, you:
have a relationship between EXPENSES and LINE ITEMS and another between EXPENSES–>JOBS–>INVOICES–>LINE ITEMS. FileMaker CANNOT deal with that kind of set up, which is why you create a new TO to represent the relationship.
- Why is the EXPENSES–>LINE ITEMS relationship a ONE TO ONE RELATIONSHIP?
because an EXPENSE is billed only ONCE, and a LINE ITEM bills ONLY for ONE EXPENSE.
- To CREATE this relationship and make it work, you need three things:
a. A new PRIMARY KEY to hook the two tables together
b. A NEW TO to represent the new relationship in your RELATIONSHIP GRAPH
c. New FIELDS on one of your layouts (The EXPENSES layout, in this case), to use the newly related data.
