Stop unique values been entered

[LLoyd]

Hi

I am want a message box to popup telling me this is a Duplicate record and
delete this row.

Thanks

 

[Max]

I am want a message box to popup telling me this is a Duplicate record and
delete this row.

Assume data will be entered in A1 down to say, A200
Select A2:A200 (A2 active)
Click Data > Validation > Settings tab
Allow: Custom
Formula: =ISERROR(MATCH(A2,$A$1:$A1,0))
Click the Error Alert tab
Enter the "pop up" error msg as desired,
eg (from your subject line): Stop! Only unique values to be entered
Click OK
Test it out ..