Forum Discussion
Unique identifier #
Hi,
I'm trying to create a list of unique identifier numbers that users can link to their activity line items with a their expenses along with a way that shows the user if a unique identifier number was already used to avoid duplication/errors. Does excel have the functionality to do this? If so, can you kindly explain? Thank you!
Let's say the identifiers will be entered in A2 and down.
Select (for example) A2:A1000. A2 should be the active cell in the selection.
On the Data tab of the ribbon, in the Data Tools group, click Data Validation.
Select Custom from the Allow drop-down.
In the Formula box, enter the formula
=COUNTIF(A$2:A$1000, A2)=1
Activate the Error Alert tab.
Enter a message to be displayed when the user tries to enter an already used number.
Click OK.
2 Replies
Let's say the identifiers will be entered in A2 and down.
Select (for example) A2:A1000. A2 should be the active cell in the selection.
On the Data tab of the ribbon, in the Data Tools group, click Data Validation.
Select Custom from the Allow drop-down.
In the Formula box, enter the formula
=COUNTIF(A$2:A$1000, A2)=1
Activate the Error Alert tab.
Enter a message to be displayed when the user tries to enter an already used number.
Click OK.
HansVogelaar thank you!
