Access 2010

Advanced field options

On the previous page, you learned about setting the data type for new fields. When you set field data type, you are really setting a rule for that field. Databases often include rules because they are a way of guaranteeing that users enter the correct type of data.

Why is this important? Computers aren't as smart as humans about certain things. While you might recognize that "two" and "2" or "NC" and "North Carolina" are the same thing, Access will not, and therefore won't group these things together. Making sure to enter your data in a standard format will help you better organize, count, and understand it.

Rules can also determine what options you have for working with that data. For example, you can only do math with data entered in number or currency fields, and you can only format text entered in memo fields.

There are three main types of rules you can set for a field: data type, character limit, and validation rules.

To change the data type for existing fields:

1. Select the field whose data type you wish to change.
2. On the Ribbon, select the Fields tab, then locate the Formatting group. Click the Data Type drop-down arrow.
   The Data Type drop-down arrow
3. Select the desired data type.
   Selecting a new field data type
4. The field data type will be changed. Depending on the data type you chose, you may notice changes to your information. For instance, since we set the data type for the Email field to Hyperlink, all of the email addresses in the field are now clickable links.
   All of the entries in this field are now formatted as clickable hyperlinks

You shouldn't change field data type unless you are certain your field data is in the correct format for the new data type. Changing a field containing only text to the Number type, for instance, will delete all of your field data. This process is often irreversible.