Access 2010: The Missing Manual

Access Data Types

Design view is a powerful place for defining a table. Design view lets you tweak all sorts of details without jumping around the ribbon (as you would if you were creating a table in Datasheet view).

One of the details is the data type of each field—a setting that tells Access what type of information you’re planning to store in it. To change the data type, make a selection in the Data Type column next to the appropriate field (Figure 2-6). Here’s where you separate the text from numbers (and other data types). The trick is choosing the best data type from the long list Access provides—you’ll get more help in the following section.

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 (and you’ll consider them again in Chapter 4).

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 2-7), to perform proper sorting, and to provide other features like calculations, ...