Microsoft Office Tutorials and References
In Depth Information
Access Data Types
Access Data Types
Memo
Large amounts of unformatted text,
up to 65,536 characters (an
averagesized chapter in a novel).
Articles, memos, letters, arrest
warrants, and other short documents.
Number
Different kinds of numbers, including
negative numbers and those that
have decimal places.
Any type of number except currency
values (for example, dollar amounts).
Stores measurements, counts, and
percentages.
Currency
Similar to Number, but optimized
for numbers that represent values of
money.
Prices, payments, and expenses.
Date/Time
A calendar date or time of day (or
both). Don’t use this field for time
intervals (the number of minutes in
a song, the length of your workout
session)—instead, use the Number
data type.
Birthdates, order dates, ship dates,
appointments, and UFO sighting
times.
Yes/No
Holds one of two values: Yes or No.
(You can also think of this as True or
False.)
Fields with exactly two options, like
male/female or approved/unap-
proved.
Hyperlink
A URL to a website, an email
address, or a file path.
www.FantasyPets.com , noreplies@
antisocial.co.uk , f:\Documents\
Report.doc .
Attachment
One or more separate files. The
content from these files is copied into
the database.
Pictures, Word documents, Excel
spreadsheets, sound files, and so on.
AutoNumber
Stores a unique, identifying number
that Access generates when you
insert a new record.
Used to uniquely identify each
record; typically set as the primary key
(page 740). Usually, every table has a
single AutoNumber field named ID.
Calculated
Generates the value automatically,
based on an expression you supply.
You can perform simple math and
combine the values from other fields.
Values that depend on other fields.
For example, if you already have a
UnitCost and a Quantity field, you
can add a TotalCost calculated field
that multiplies them together.
OLE Object
Holds embedded binary data,
according to the Windows OLE (object
linking and embedding) standard.
Rarely used, because it leads to
database bloat and other problems.
The Attachment field is almost always
a better choice.
Some types of pictures and
documents from other programs. Mostly
used in old-school Access databases.
Nowadays, database designers use
the Attachment data type instead of
the OLE Object data type.
The—following—sections—describe—each—data—type—except—for—OLE—Object,—which—is—a—
holdover—from—the—dark—ages—of—Access—databases.—Each—section—also—describes—any—
important—field—properties—that—are—unique—to—that—data—type.
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