Microsoft Office Tutorials and References
In Depth Information
Session 2.1
Determine the properties of each field. You need to identify the properties , or charac-
teristics, of each field so that the DBMS knows how to store, display, and process the
field values. These properties include the field’s name, maximum number of characters
or digits, description, valid values, and other field characteristics. You will learn more
about field properties later in this tutorial.
The Position table you need to create will contain the fields shown in Figure 2-2, plus the
EmployerID field as a foreign key. Before you create the new Northeast database and the
Position table, you first need to learn some guidelines for setting field properties.
Guidelines for Setting Field Properties
As just noted, the last step of database design is to determine which values to assign to the
properties, such as the name and data type, of each field. When you select or enter a
value for a property, you set the property. Access has rules for naming fields, choosing
data types, and setting other properties for fields.
Naming Fields and Objects
You must name each field, table, and other object in an Access database. Access then
stores these items in the database, using the names you supply. It’s best to choose a field
or object name that describes the purpose or contents of the field or object, so that later
you can easily remember what the name represents. For example, the three tables in the
Northeast database will be named Employer, NAICS, and Position, because these names
suggest their contents.
The following rules apply to naming fields and objects in Access:
• A name can be up to 64 characters long.
• A name can contain letters, numbers, spaces, and special characters, except for a period
(.), exclamation mark (!), accent grave (`), and square brackets ([ ]).
• A name cannot start with a space.
• A table or query name must be unique within a database. A field name must be unique
within a table, but it can be used again in another table.
In addition, experienced users of databases follow these conventions for naming fields
and objects:
• Capitalize the first letter of each word in the name.
• Avoid extremely long names because they are difficult to remember and reference.
• Use standard abbreviations, such as Num for Number, Amt for Amount, and Qty for Quantity.
• Avoid using spaces or special characters in names. According to standard database nam-
ing conventions, spaces and special characters should not be included in names.
However, you can change how a field name is displayed in database objects—tables,
forms, reports, and so on—by setting the field’s Caption property. (You’ll learn about set-
ting the Caption property later in this tutorial.)
Assigning Field Data Types
You must assign a data type for each field. The data type determines what field values you
can enter for the field and what other properties the field will have. For example, the
Position table will include a StartDate field, which will store date values, so you will
assign the date/time data type to this field. Then Access will allow you to enter and
manipulate only dates or times as values in the StartDate field.
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