How to create a drop-down list in Excel to manage data and prevent mistakes

You can easily create a drop-down list in Excel to limit the values that can be entered in a column. Here's how to set one up ...
TechRepublic

Use Excel data validation to prevent duplicate values in a column

Use Excel data validation to prevent duplicate values in a column Your email has been sent Prevent duplicates before they happen by combining a simple function with data validation. Excel has built-in ...
Ars Technica

Custom validation in Excel using VBA?

I've got an Excel 97 worksheet in which I need to validate some cells. No problem, I'll just use Data->Validate, right? Wrong. The built in validation works well enough as long as the user doesn't ...