As you can see, the table design begins to take on a life of its own. After you’ve created the single
table, it becomes even more difficult to maintain. You begin to realize that you have to input the
customer information for every sale a customer makes (repeating the information over and over).
The same is true for the items purchased for each sale, which is multiple items for each sale (thus,
duplicating information again). This makes the system more inefficient and prone to data-entry
mistakes. The information stored in the table becomes inefficiently maintained — many fields may
not be appropriate for each record, and the table ends up with a lot of empty fields.
It’s important to create tables that hold the minimum of information while still making the system
easy to use and flexible enough to grow. To accomplish this, you need to consider making more
than one table, with each table containing records with fields that are related only to the focus of
that table. Then, after you create the tables, you link them so that you’re able to glean useful infor-
mation from them. Although this process sounds extremely complex, the actual implementation is
relatively easy. Again, this process of creating multiple tables from a single table is known as
nor-
malization
(or normalizing your tables).
Access Database Objects and Views
If you’re new to databases (or even if you’re an experienced database user), you need to understand
some key concepts before starting to build Access databases. The Access database contains seven
types of top-level objects, which consist of the data and tools that you need to use Access:
n
Table:
Holds the actual data
n
Query:
Searches for, sorts, and retrieves specific data
n
Form:
Lets you enter and display data in a customized format
n
Report:
Displays and prints formatted data
n
Pages:
Publishes data to a corporate intranet
n
Macro:
Automates tasks without programming
n
Module:
Contains programs written in the Visual Basic for Applications (VBA) program-
ming language
Datasheets
Datasheets are one of the many ways by which you can view data in Access. Although not a
database object, a datasheet displays a list of records from a table in a format similar to an account-
ing spreadsheet or Excel worksheet. A datasheet displays data as a series of rows and columns
(comparable to an Excel spreadsheet). A datasheet displays a table’s information in its raw form.
The datasheet view is the default mode for displaying all fields for all records.
You scroll through the datasheet using the directional keys on your keyboard. You can also display
related records in other tables while in a datasheet. In addition, you can make changes to the dis-
played data.
8
Access Building Blocks
Part I
05_046732 ch01.qxp 11/21/06 8:44 AM Page 8
|
|