Prevent Duplicate Entries in Excel with Data Validation
You can prevent duplicate entries from creeping into an Excel worksheet when you protect selected cells with Data Validation.
In this case, you write a Formula that will return either TRUE or FALSE as the answer - i.e. you create a "logical formula." Watch this tutorial as I walk you through each step.
I also show you how to identify "existing" duplicate values in a data set - once again, using Data Validation.
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Danny Rocks
The Company Rocks