How to avoid duplicate entries in an Excel worksheet using data validation
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How to avoid duplicate entries in an Excel worksheet using data validation

How can you avoid duplicate entries right from the beginning of your work in Excel: Use data validation in combination with the countif function. References to cell ranges in the countif function must be 'absolute'. Watch the training video to see how the process can be easily implemented.
How to implement the process:
  1. Select the cells where you are going to make entries. You can later expand the range automatically
  2. Click on data tab in the ribbon, select data validation and in the new window under 'Allow' select 'custom' and in the formula text box we write '=countif($A$5:$A$10,$A$5)<=1'. This formula compares every new entry with the data already in the range and ensures no two IDs are the same in our example.



How to avoid duplicate entries in an Excel worksheet using data validation