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A default value can be an
expression, as well as a number or a text string.
Because the Default Value for Number and Currency data types is set to 0 (zero), by
default, these fields are set automatically to 0 when you add a new record. In many situations,
such as medical test results and many financial applications, zero is not an appropriate default
value for numeric fields. Be sure to verify that zero is an appropriate default value in your Access
applications.
n Validation Rule: Ensures that data entered into the field conforms to some business rule,
such as ???greater than zero,??? ???date must occur after January 1, 2000,??? and so on.
n Validation Text: Displays a message when data fails validation.
n Required: Specifies whether you must enter a value into a field.
n Allow Zero Length: Determines whether you may enter an empty string (??????) into a text
field type to distinguish it from a null value.
n Indexed: Speeds up data access and (if desired) limits data to unique values.


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