When you design a database in Access 2010, you decide what type each field will be. Here are tips for when to use which type of field.
| Field Type | What It Holds |
|---|---|
| Text | Text up to 255 characters long (including spaces and punctuation). Use a Text field, not a Number field, for codes — such as phone numbers, ZIP codes, and other postcodes — even if they look like numbers. |
| Memo | Like a Text field, but more of them — up to 65,536 characters. A memo field can contain rich (formatted) text, and you can set it to Append Only, so that it can accumulate text notes, without allowing the user to delete what’s already there. |
| Number | Only numbers. You may use + or – before the number, and a decimal point. If you plan to do math with a field, use a Number or Currency field. |
| Currency | Numbers with a currency sign in front of them ($, ¥, and so on). |
| AutoNumber | Numbers unique to each record and assigned by Access as you add records, starting at 1. Use an AutoNumber field as the primary key field for most tables. |
| Date/Time | Dates, times, or both. |
| OLE Object | Object Linking and Embedding. Don’t use it when creating a new database; use the new Attachment type instead because it stores data more efficiently. |
| Hyperlink | This text string is formatted as a hyperlink. (If you click the link, it takes you to the page.) This is especially useful if there’s related information on the Web. |
| Yes/No | Yes or no (a particular condition is, or isn’t, in effect) — or other two-word sets, such as Yes/No field if you want to display the field as a check box on forms. |
| Attachment | You can store one or more entire files — pictures, sound, Word documents, even video — in one Attachment field. |
| Calculated | You enter a formula that Access uses to calculate the value of this field based on other fields in the table. Use a Calculated field when a calculated value will be used in many queries, forms, and reports. |
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Source:http://www.dummies.com/how-to/content/tips-for-choosing-field-types-in-access-2010.html
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