How to Prevent Duplicate Values in a Database in Access 2003
You can keep your Microsoft Access 2003 database free of confusing clutter by preventing duplicate values. For example, if you create a file where the key field is defined as the customer number field, you'll want the system to ensure that each record in the file has a unique customer number. Here are some steps to prevent duplicate values in a database in Access 2003.
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Instructions
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Preventing Duplicate Values in a Field
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1
Open Microsoft Access 2003 by clicking on the appropriate icon on your computer desktop.
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2
Open a table in Design view.
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3
In the upper part of the screen, click on the field where you want to prevent duplicate entries.
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4
In the lower part of the screen, click the Indexed property box and select "Yes" (No Duplicates).
Preventing Duplicate Entries in a Combination of Fields
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Open the table in Design view.
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Click Indexes on the toolbar, or open the View menu and choose "Index."
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Type a name for the index in the Index Name column.
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Go to the Field Name column and click the arrow.
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Select the first field for the index.
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Repeat, selecting as many fields as necessary.
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Leave the Index window open.
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Click on the new index name at the top.
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At the bottom of the screen, click the "Unique Property" box and set it to "Yes."
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Tips & Warnings
If records with duplicate key values already exist in a physical file, the associated logical file cannot have the unique keyword specified.
When the unique keyword is specified for a file, any record added to the file cannot have a key value that duplicates the key value of an existing record in the file, regardless of the file used to add the new record.
