Microsoft Office Tutorials and References
In Depth Information
Naming Tables and Fields
In designing your database, you must name the tables and fi elds. Thus, before
beginning the design process, you must understand the rules for table and fi eld names,
which are:
1. Names can be up to 64 characters in length.
2. Names can contain letters, digits, and spaces, as well as most of the punctuation
symbols.
3. Names cannot contain periods (.), exclamation points (!), accent graves ( `), or
square brackets ([ ]).
4. The same name cannot be used for two different fi elds in the same table.
The approach to naming tables and fi elds used in this text is to begin the names
with an uppercase letter and to use lowercase for the other letters. In multiple-word
names, each word begins with an uppercase letter, and there is a space between words (for
example, Client Number). You should know that there are other approaches. Some people
omit the space (ClientNumber). Still others use an underscore in place of the space
(Client_Number). Finally, some use an underscore in place of a space, but use the same
case for all letters (CLIENT_NUMBER or client_number).
Naming Fields
Access 2007 has a number
of reserved words, words
that have a special
meaning to Access. You
cannot use these reserved
words as fi eld names.
For example, Name is a
reserved word and could
not be used in the Client
table to describe a client’s
name. For a complete
list of reserved words
in Access 2007, consult
Access Help.
Identifying the Tables
Now that you know the rules for naming tables and fi elds, you are ready to begin
the design process. The fi rst step is to identify the main objects involved in the
requirements. For the JSP Recruiters database, the main objects are clients and recruiters. This
leads to two tables, which you must name. Reasonable names for these two tables are:
Client
Recruiter
Determining the Primary Keys
The next step is to identify the fi elds that will be the primary keys. Client numbers
uniquely identify clients, and recruiter numbers uniquely identify recruiters. Thus, the
primary key for the Client table is the client number, and the primary key for the Recruiter
table is the recruiter number. Reasonable names for these fi elds would be Client Number
and Recruiter Number, respectively. Adding these primary keys to the tables gives:
Client (Client Number)
Recruiter (Recruiter Number)
Determining Additional Fields
After identifying the primary keys, you need to determine and name the additional
fi elds. In addition to the client number, the Client Address Information shown in
Figure 1–2a contains the client name, street, city, state, and postal code. These would be
fi elds in the Client table. The Client Financial Information shown in Figure 1–2b on the
previous page also contains the client number and client name, which are already included
in the Client table. The fi nancial information also contains the amount paid and the
current due. Adding the amount paid and current due fi elds to those already identifi ed in the
Client table and assigning reasonable names gives:
Client (Client Number, Client Name, Street, City, State, Postal Code,
Amount Paid, Current Due)
Database Design
Language (DBDL)
DBDL is a commonly
accepted shorthand
representation for
showing the structure
of a relational database.
You write the name of
the table and then within
parentheses you list all
the columns in the table.
If the columns continue
beyond one line, indent
the subsequent lines.
 
Search JabSto ::




Custom Search