Microsoft Office Tutorials and References
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Eliminating duplicate values
Eliminating duplicate values
Each row in a database table should contain unique and
non-duplicated data. However, because using a query enables
you to select only some of the fields, the values in those
selected fields can be duplicated. This can be very useful when
you are given a table of data from another source outside of
Access and you want to identify a unique list of values in a
particular field.
For our example, we have a list of Customer records where we
have more than one customer in each city and we want to
display a list of unique city names.
Eliminate duplicate rows
1 Select and optionally sort the field.
2 Eliminate any NULL values by typing Is Not Null in the criteria.
3 Click Property Sheet to display the Property Sheet, if it is not
already shown. If your Property Sheet does not show the properties
we have displayed, click anywhere on the gray background to see
the query properties; the property sheet can display either query or
field properties depending on where you last clicked in the query
design tool.
4 Change the query property Unique Values to Yes.
TIP You can also find unique values by creating a summary
query, where you create a query, select a single field, and then
click the Totals button. By default, the field then uses a Group By Total,
which produces an output similar to the method described here.
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