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Data validation exists in list

Excel formula: Data validation exists in list
Generic formula 
=COUNTIF(list,A1)>0
Explanation 

Note: Excel has a built-in data validation rules for dropdown lists. This page explains how to create a your own validation rule for lists when you don't want the dropdown behavior.

To allow only values from a list in a cell, you can use data validation with a custom formula based on the COUNTIF function.

In the example shown, the data validation applied to C5:C9 is:

=COUNTIF(colors,C5)>0

How this formula works

Data validation rules are triggered when a user adds or changes a cell value.

In this case, the COUNTIF function is part of an expression that returns TRUE when a value exists in a specified range or list, and FALSE if not.

The COUNTIF function simply counts occurrences of the value in the list. Any count greater than zero will pass validation.

Note:  Cell references in data validation formulas are relative to the upper left cell in the range selected when the validation rule is defined, in this case C5.

Author 
Dave Bruns

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