Changing Data Attributes

As you learned in the previous chapter, Microsoft Access provides a number of different data types. These data types help Access work more efficiently with your data and also provide a base level of data validation; for example, you can enter only numbers in a Number or Currency field.

When you initially design your database, you should match the data type and length of each field to its intended use. You might discover, however, that a field you thought would contain only numbers (such as a U.S. ZIP Code) must now contain some letters (perhaps because you’ve started doing business in Canada). You might find that one or more number fields need to hold larger values or a different number of decimal places. Access allows you to change the data type and length of many fields, even after you’ve entered data in them.