A colleague runs the car-park lottery for our organisation. She uses an
Excel spreadsheet witha round 1500 entries. The sheet identifies each staff
member by means of their exclusive payroll number. The lottery is run 4
times a year. However, she has a problem in that when a member rings up to
register sometimes neither her nor the member is able to tell if they have
registered before. She wants to ensure that it is not possible to enter a
person twice.

So, what would be ideal, is when she has entered the payroll number if there
is no pre-existing entry Excel will allow her to proceed to the next field,
if there is this will be flagged up and further entry would not be
permitted.

I would be grateful if anyone could point me in the direction of a solution.

Best wishes,

Ted