Microsoft Office Tutorials and References
In Depth Information
Access Data Types
Access Data Types
Depending on the data type you choose, you can adjust other field properties to nail
down your data type even more precisely. If you use a text data type, then you use
field properties to set the maximum length. If you choose a decimal value, then you
use field properties to set the number of decimal places. You set field properties in
the Field Properties part of the Design view, which appears just under the field list.
You’ll learn more about field properties throughout this chapter.
The most important decision you make for any field is choosing its data type. The
data type tells Access what sort of information you plan to store in that field. Access
uses this information to reject values that don’t make sense (see Figure 26-7), to
perform proper sorting, and to provide other features like calculations, summaries,
and filtering.
Figure 26-7:
This currency field absolutely
does not allow text. Access
lets you fix the problem by
entering a new value (the right
choice) or changing the field
data type to text so that it
allows anything (the absolutely
wrong choice).
Note: A field can have only one data type. You can’t create a field that can store two or three different
data types, because Access wouldn’t have enough information to manage the field properly. (Instead, in
this situation, you probably need two separate fields.)
As you learned earlier, there are three basic types of data in the world: text, numbers,
and dates. However, Access actually provides a whopping data types, which 12
clude many more specialized choices. Before picking the right data type, it’s a good
idea to review all your choices. Table 26-1 shows an overview of the menu options in
the Data Type list. (The Lookup Wizard choice isn’t included, because it isn’t a real
data type. Instead, this menu option launches the Lookup wizard, which lets you set
a list of allowed values. You’ll learn more about this on page 756.)
Table 26-1. Access data types
Data Type
Description
Examples
Text
Numbers, letters, punctuation,
and symbols, up to a maximum of
255 characters (an average-sized
paragraph).
Names, addresses, phone numbers,
and product descriptions. This data
type is the most common.
 
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