Howdy,

I need a way to prevent a user from entering duplicate data in a range of
cells (ex. C6:C36). I need to prevent the user from entering an invoice
number twice. I don't know if this is something for Data Validation or not. I
have been trying that and cant get it to work.

Ryan,

Select C6:C36, the use Data / Validation... on the "Settings" tab, Select Custom under "Allow"
and use the formula

=COUNTIF($C$6:$C$36,C6)=1

HTH,
Bernie
MS Excel MVP


"Ryan" wrote in message
...
Howdy,

I need a way to prevent a user from entering duplicate data in a range of
cells (ex. C6:C36). I need to prevent the user from entering an invoice
number twice. I don't know if this is something for Data Validation or not. I
have been trying that and cant get it to work.

Thanks a lot, thats helped out alot

"Bernie Deitrick" wrote:

Ryan,

Select C6:C36, the use Data / Validation... on the "Settings" tab, Select Custom under "Allow"
and use the formula

=COUNTIF($C$6:$C$36,C6)=1

HTH,
Bernie
MS Excel MVP


"Ryan" wrote in message
...
Howdy,

I need a way to prevent a user from entering duplicate data in a range of
cells (ex. C6:C36). I need to prevent the user from entering an invoice
number twice. I don't know if this is something for Data Validation or not. I
have been trying that and cant get it to work.

What If I already have validation Allow=List AND I want to detect duplicates
in range say H13:H20

Validation:
Allow: List
Source: =AccountList

John

"Bernie Deitrick" wrote:

Ryan,

Select C6:C36, the use Data / Validation... on the "Settings" tab, Select Custom under "Allow"
and use the formula

=COUNTIF($C$6:$C$36,C6)=1

HTH,
Bernie
MS Excel MVP


"Ryan" wrote in message
...
Howdy,

I need a way to prevent a user from entering duplicate data in a range of
cells (ex. C6:C36). I need to prevent the user from entering an invoice
number twice. I don't know if this is something for Data Validation or not. I
have been trying that and cant get it to work.