Access 2007 for Starters: The Missing Manual

Access Data Types

Design view's a much more powerful place for defining a table than Datasheet view. As you'll see throughout this chapter, Design view allows you to tweak all sorts of details that are hidden in Datasheet view (or just awkward to change).

One of these is the data type of your field—a setting that tells Access what type of information you're planning to store. 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's 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, there are other field properties that you can adjust 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'll 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 ...