# duplicate invoice formula

Posted by Cliff on July 30, 2000 10:37 PM

I just read a formula that will notify the user when a duplicate invoice number is entered. The formula is this =isna(vlookup(A3,A$1:A2,1,false)) which I used and it worked great on the worksheet I entered it in. But I'm needing to use this for more than one worksheet in the same workbook. I know that the above formula will work on page 1, but how would I change it for 2nd, 3rd, etc.. sheets. I have a purchase journal set up in excel that has 1 page for each week in the month, labeled week 1, week 2, etc..

thanks in advance.

Posted by Celia on August 02, 0100 12:55 AM

Cliff

So far, have not been able to work out a direct method of data validation that will take into account all the sheets. Here is a roundabout way of doing it :-

In each sheet put the following formula in row 2 of a column that is not used (lets say column CF) and fill the whole column :-

=IF(COUNTIF(Week1,A2)+COUNTIF(Week2,A2)+ COUNTIF(Week3,A2) COUNTIF(Week4,A2) COUNTIF(Week5,A2)>1,"X","")

In each sheet, select column A and in the data validation formula box put :-

=CF<>X

If you dont like the above, you could use data validation for each sheet instead, which I guess would be better than not having it at all and together with conditional formatting, you should be fairly well covered.

To set up data validation on individual sheets, select column A and in the data validation formula box put :-

=COUNTIF($A$2:$A$10000,A1)=1

Celia

Posted by Celia on August 02, 0100 12:59 AM

Correction

I missed out some + signs :-

=IF(COUNTIF(Week1,A2)+COUNTIF(Week2,A2)+ COUNTIF(Week3,A2)+COUNTIF(Week4,A2)+COUNTIF(Week5,A2)>1,"X","")

Celia

Posted by Celia on August 01, 0100 4:56 AM

thanks in advance.

Cliff

Two suggestions to do what you want are set out below.

In both cases I have assumed that :-

1.You have a workbook that already has four sheets named Week1, Week2, Week3, Week4.

2.Invoice numbers get entered in Column A of each sheet starting from cell A2 (cell A1 being used as the column header).

3.There will be no more than 10,000 invoices in any one week.

CONDITIONAL FORMATTING

This method will highlight any invoice numbers that are duplicates as and when an invoice number is entered in Column A of any of the four sheets.

1.Create four names as follows :-

Name : Week1

Refers to : =Week1!$A$2:$A$10000

Name : Week2

Refers to : =Week2!$A$2:$A$10000

Name : Week3

Refers to : =Week3!$A$2:$A$10000

Name : Week4

Refers to : =Week4!$A$2:$A$10000

2.Go to sheet Week1 and select Column A

3.Go to Format/Conditional Formatting

4.Select Formula Is in the first box and type into the second box :-

=IF(COUNTIF(Week1,A1)+ COUNTIF(Week2,A1)+ COUNTIF(Week3,A1)+ COUNTIF(Week4,A1)>1,TRUE,FALSE)

5.Select Format
and select the format you want to use to identify duplicate invoice numbers. Click OK.

6.Repeat steps 2 thru 5 for each of the sheets Week2, Week3, Week4

WORKSHEET FORMULA

This method identifies in a separate column (assumed to be Column B), all entries that are duplicates in Column A of all four sheets. The words Duplicate No. will be displayed in Column B against any duplicate invoice numbers.

1.Create names as in step 1 of CONDITIONAL FORMATTING above

2.Go to sheet Week1 and enter the following formula in cell B2 :-

=IF(COUNTIF(Week1,A1)+COUNTIF(Week2,A1)+COUNTIF(Week3,A1) +COUNTIF(Week4,A1)>1,"Duplicate No.","")

3.Drag the formula in cell B2 down as far as required

2.Repeat steps 2 & 3 for each of the sheets Week2, Week3, Week4

Alternatively, it must also be possible to prevent users inputting duplicates by using data validation.

Celia

Posted by Celia on August 01, 0100 6:07 AM

Re: Correction

Cliff

In the formulas wherever it reads A1, it should A2

Celia

Posted by david on July 31, 0100 10:26 PM

Sorry not familiar with isna but

=ISNA(VLOOKUP(Sheet1!a3,Sheet2:Sheet3!A1:A2,1,FALSE))

jUST NAME YOUR SHEETS

I just read a formula that will notify the user when a duplicate invoice number is entered. The formula is this =isna(vlookup(A3,A$1:A2,1,false)) which I used and it worked great on the worksheet I entered it in. But I'm needing to use this for more than one worksheet in the same workbook. I know that the above formula will work on page 1, but how would I change it for 2nd, 3rd, etc.. sheets. I have a purchase journal set up in excel that has 1 page for each week in the month, labeled week 1, week 2, etc.. thanks in advance.

Posted by cliff on August 01, 0100 10:33 PM

Celia,

Thank you so much for all your help. Everything has worked great and I appreciate your knowledge and help. For this though, I have it set up using your top formula above by turning duplicates red and a line through the invoice number. But with the people I work with I'd rather use data validation that will stop duplicates from being entered. I tried to enter your formula several ways, even combining the original formula yours and a couple others but I either get a formula error or a message saying I can't use data from other sheets. What am I doing wrong?? I modified your formula to fit my journal, I have 5 weeks and the cell range is c9:c38. Another question, know any excel chat rooms??