Microsoft Access 2010 Bible

(Rick Simeone) #1

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Introduction


The diagram in Figure FM.2 displays the table schema in the Collectible Mini Cars example. As
you’ll learn in Part I of this book, the lines, arrows, and symbols between the tables mean some-
thing important and communicate to the developer how the data interacts. You’ll learn terms like
table, field, record, relationship, referential integrity, normalization, primary keys, and foreign keys as
you begin to understand how tables work within a database.

FIGURE FM.2
The Collectible Mini Cars relationship diagram

The example database consists of the eight core tables shown in Figure FM.2. Many of the smaller
tables are lookup tables, the sole purpose of which is to provide a list of valid selections. The larger
tables hold data used by the database application itself. All these tables include a number of data
fields that are used as the definitions of the data. The lines between the tables show how tables are
related:

l tblSales contains the primary sales information, including the sale date, the invoice
number, the buyer ID (which links to tblContacts to retrieve information about the
buyer), and various other financial information.
l tblSalesLineItems contains fields for the individual line items that make up a sale. A
sale may contain a variety of items. Several products may be sold to a single buyer at one
time, or a shipment may be sent to an alternate address. The sales form (frmSales) pro-
vides data entry of an invoice and an unlimited number of line items stored in this table.
The data fields in tblSalesLineItems include the invoice number, which links the
invoice to the line items as well as the quantity purchased. The ProductID field (which
links to tblProducts) is used to retrieve product information, including the item
description, list price, and wholesale cost.

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