Microsoft Office Tutorials and References
In Depth Information
Because Sarah wants her staff to store only standard 10-digit U.S. phone numbers for
customers, the input mask you’ve created will enforce the standard entry and display for-
mat that Sarah desires.
Understanding When to Use Input Masks
An input mask is appropriate for a field only if all field values have a consistent format. For
example, you can use an input mask with hyphens as literal display characters to store U.S.
phone numbers in a consistent format of 987-654-3210. However, a multinational company
would not be able to use an input mask to store phone numbers from all countries, because
international phone numbers do not have a consistent format. For another example, U.S. zip
codes have a consistent format, and you could use an input mask of 00000#9999 to enter
and display U.S. zip codes such as 98765 and 98765-4321, but you could not use an input
mask if you need to store and display foreign postal codes in the same field. If you need to
store and display phone numbers, zip/postal codes, and other fields in a variety of formats,
it’s best to define them as Text fields without an input mask and let users enter field values
and the literal display characters.
After the change to the Phone field’s input mask, Access gave you the option to update,
selectively and automatically, the Phone field’s Input Mask property in other objects in the
database. Sarah asks if there’s an easy way to determine which objects are affected by
changes made to other objects. To show Sarah how to determine the dependencies among
objects in an Access database, you’ll open the Object Dependencies pane.
Identifying Object Dependencies
An object dependency exists between two objects when a change to the properties of
data in one object affects the properties of data in the other object. Dependencies
between Access objects (tables, queries, forms, and so on) can occur in various ways. For
example, the tblContract and tblInvoice tables are dependent on each other because they
have a one-to-many relationship. As another example, because the tblContract table uses
the qryCustomersByName query to obtain the Customer field to display along with the
CustomerID field, these two tables have a dependency. Any query, form, or other object
that uses fields from the tblCustomer table is dependent on the tblCustomer table. Any
form or report that uses fields from a query is directly dependent on the query and is
indirectly dependent on the tables that provide the data to the query. Large databases
contain hundreds of objects, so it would be useful to have a way to view the dependen-
cies among objects easily before you attempt to delete or modify an object. The Object
Dependencies pane displays a collapsible list of the dependencies among the objects in
an Access database; you click the list’s expand indicators to show or hide different levels
of dependencies. Next, you’ll open the Object Dependencies pane to show Sarah the
object dependencies in the Panorama database.
To open and use the Object Dependencies pane:
1. Click the Database Tools tab on the Ribbon, and then, in the Show/Hide group,
click the Object Dependencies button to open the Object Dependencies pane,
and then drag the left edge of the pane to the left until the horizontal scroll bar at
the bottom of the pane disappears. See Figure 5-40.