If than or Match formula???

[dduvall]

thanks in advance... trying to make an impression at work and i'm not exactly at all the best with excel. i need a formula which i think would help prevent errors.

spreadsheet is basic, 3 columns (inv, date sub, date pros)
i need the formula to determine if an "inv" has been entered multiple times.
if you enter inv#123 this week and 2 weeks from now enter inv#123 again i need the spreadsheet to pop up "NO" or "BAD" (word doesn't matter really).

I thought of the "IF" formula but obviously i'm not exactly the best here. Any help would be great.

thanks....

[NBVC]

Welcome to the forum,

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[NBVC]

Thanks for taking the time to read and comply with the rule ... and sorry that nobody has gotten back to you....

... have you considered data validation?

Say the values you are entering are in range E2:E100...with heading in E1

Then you would select E2 to E100 and go to Data|Validation..

Select Custom and then enter formula:

=COUNTIF($E$1:E2,E2)=1

Now it will only allow you to enter any value only once in that range... as you go down.

If you may have some numbers already down the list and might be replacing numbers higher up, but do not want repeats, then use formula:

=COUNTIF($E$1:$E$100,E2)=1

Click Ok and test.

... Note: You can change the error message via Data Validation Error Alert tab.