Use Excel data validation to prevent duplicate values in a column Your email has been sent Prevent duplicates before they happen by combining a simple function with data validation. Excel has ...

Again, select the Data tab in Excel. Click on the Data Validation icon to reveal a dropdown menu. From that menu, you must select Clear Validation Circles.

Excel's data validation feature is more versatile than you might think. Learn how to use literal values, input values, list values, and even formulas to restrict input date values using data ...