Preventing Duplicate Entries within a column

B

Bruce

Is there an easy way to prevent creating duplicate
entries within a given column in Excel?
Alternately....is there a way to automatcially highlight
a cell / row when a duplicate entry is created within a
given column?
 
J

Jim May

Assuming your entry-range begins in A3 and downward to A100
Select Cell A4, then at the menu, select Data, Validation, Allow: Custom
In the formula Box enter:
=IF(COUNTIF($A$3:$A4,$A4)>1,FALSE,TRUE)
then OK (out).
While A4 is Blank or empty, Copy it and paste from A5:A100.
Done.
HTH
 
R

Rob van Gelder

To highlight duplicates:
Select column A
From Format menu | Conditional Formatting
Formula Is: =COUNTIF($A:$A, $A1)>1
Then format as Bold, or Red or whatever.
 
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