Data Types come in all different shapes and sizes dependent upon the data you want to store in your individual fields.
And, although Access 2007 does a decent job of automatically detecting the data type for a field that you create, there will be times when you need to override the choice that Access makes.
You can set the data type for any field in either Datasheet View or Design View.
The following table describes some of the more common data types available for fields in Access.
Use for text, or text and numbers that are not used in calculations (for example, a product ID).
Up to 255 characters.
Use for text greater than 255 characters in length, or for text that uses rich text formatting. Notes, lengthy descriptions, and paragraphs with formatting such as bold or italics are good examples of where you would use a Memo field.
Up to 1 gigabyte of characters, or 2 gigabytes of storage (2 bytes per character), of which you can display 65,535 characters in a control.
Use for storing numbers to be used in calculations, except for monetary values (use the Currency for data type for monetary values).
1, 2, 4, or 8 bytes, or 16 bytes when used for replication ID.
Use for storing date/time values. Note that each value stored includes both a date component and a time component.
Use for storing monetary values (currency).
Use for generating unique values that can be used as a primary key. Note that AutoNumber fields can be incremented sequentially, by a specified increment, or chosen randomly.
4 bytes or 16 bytes when used for replication ID.
Use for True/False fields that can hold one of two possible values: Yes/No or True/False, for example.
1 bit (8 bits = 1 byte).
Use for storing hyperlinks to provide single-click access to Web pages through a URL (Uniform Resource Locator) or files through a name in UNC (universal naming convention) format. You can also link to Access objects stored in a database.
Up to 1 gigabyte of characters, or 2 gigabytes of storage (2 bytes per character), of which you can display 65,535 characters.