Database Reference
In-Depth Information
Specifying the type of data
You learned in Chapter 2, “Create databases and simple tables,” that a field's data type
restricts entries in that field to a specific type of data. For example, if the data type is set
to Number and you try to enter text, Access refuses the entry and displays a warning.
When setting the data type of a field in a table in Design view, you can choose from the
following types:
▪
Short Text
Use for text fields that require up to 255 alphanumeric characters.
▪
Long Text
Use for text fields that require up to 65,535 alphanumeric characters.
TIP
When adding fields in Datasheet view, you can assign the Rich Text data type to
fields that require up to 65,535 alphanumeric characters with character formatting.
This is actually the Long Text data type with the Text Format property set to Rich Text
instead of Plain Text.
▪
Number
Use for numeric values. The size of the entry is controlled by the Field Size
property.
SEE ALSO
For information about the possible settings for Number fields, see “Setting
the field size” later in this chapter.
▪
Date/Time
Use for dates in the years from 100 through 9999. Dates and times can
be expressed in a variety of formats.
▪
Currency
Use for decimal values with up to 15 digits to the left of the decimal point
and up to 4 digits to the right.
▪
AutoNumber
Use when you want Access to assign a unique number to each new
record. If you delete a record, its AutoNumber value is not reused, and remaining
records are not updated.
▪
Yes/No
Use for fields that can have only two possible mutually exclusive values, such
as True or False.
TIP
In the database world, the Yes/No data type is more commonly called
Boolean
,
in honor of George Boole, an early mathematician and logistician.
▪
OLE Object
Use to hold a graphic or object such as a Microsoft Excel worksheet or
Microsoft Word document.
▪
Hyperlink
Use to hold a clickable path to a folder on your hard disk, a network
location, or a website.
