Microsoft Office Tutorials and References
In Depth Information
Session 2.1
Figure 2-4 lists the 10 data types available in Access, describes the field values allowed
for each data type, explains when you should use each data type, and indicates the field
size of each data type.
Data types for fields
Figure 2-4
Data Type
Description
Field Size
Text
Allows field values containing letters, digits, spaces, and special characters.
0 to 255 characters; 50 characters
Use for names, addresses, descriptions, and fields containing digits that are
default
not used in calculations.
Memo
Allows field values containing letters, digits, spaces, and special characters.
1 to 65,535 characters; exact size is
Use for long comments and explanations.
determined by entry
Number
Allows positive and negative numbers as field values. Numbers can contain
1 to 15 digits
digits, a decimal point, commas, a plus sign, and a minus sign. Use for
fields that you will use in calculations, except calculations involving money.
Date/Time
Allows field values containing valid dates and times from January 1, 100 to
8 bytes
December 31, 9999. Dates can be entered in mm/dd/yy (month, day, year)
format, several other date formats, or a variety of time formats, such
as 10:35 PM. You can perform calculations on dates and times, and you can
sort them. For example, you can determine the number of days between
two dates.
Currency
Allows field values similar to those for the number data type. Unlike
Accurate to 15 digits on the left
calculations with number data type decimal values, calculations performed
side of the decimal separator and
using the currency data type are not subject to round-off error.
to 4 digits on the right side
AutoNumber
Consists of integers with values controlled by Access. Access automatically
9 digits
inserts a value in the field as each new record is created. You can specify
sequential numbering or random numbering, which guarantees a unique field
value, so that such a field can serve as a table’s primary key.
Yes/No
Limits field values to yes and no, on and off, or true and false. Use for fields
1 character
that indicate the presence or absence of a condition, such as whether an
order has been filled or whether an employee is eligible for the company
dental plan.
OLE Object
Allows field values that are created in other programs as objects, such as
1 gigabyte maximum; exact size
photographs, video images, graphics, drawings, sound recordings, voice-mail
depends on object size
messages, spreadsheets, and word-processing documents. These objects can
be linked or embedded.
Hyperlink
Consists of text used as a hyperlink address. A hyperlink address can have up
Up to 64,000 characters total for
to three parts: the text that appears in a field or control; the path to a file or
the three parts of a hyperlink
page; and a location within the file or page. Hyperlinks help you to connect
data type
your application easily to the Internet or an intranet.
Lookup Wizard
Creates a field that lets you look up a value in another table or in a
Same size as the primary key field
predefined list of values.
used to perform the lookup
Setting Field Sizes
The Field Size property defines a field value’s maximum storage size for text, number, and
AutoNumber fields only. The other data types have no Field Size property because their
storage size is either a fixed, predetermined amount or is determined automatically by the
field value itself, as shown in Figure 2-4. A text field has a default field size of 50 charac-
ters; you can also set its field size by entering a number from 0 to 255. For example, the
PositionTitle and ReferredBy fields in the Position table will be text fields with a size of
30 characters each. This field size will accommodate the values that will be entered in
each of these fields (titles and names, respectively).
 
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