External Data Validation

The data validation feature of Excel is quite handy. You can use the feature to specify a range of values that are considered acceptable for user input. Normally, Excel expects you to specify your validation range as being on the same worksheet where you are defining the validation rule. If you try to enter a range that is on another worksheet or in another workbook, Excel balks and gives you an error message.

What if you want the validation range to be on another worksheet, just so you don't clutter up the current worksheet with extraneous data? The easiest way to do that is to follow these general steps:

1. Select the range of cells you want to use as your data validation values.
2. Choose Name from the Insert menu, and then Define from the submenu. Excel displays the Define Name dialog box. (Click here to see a related figure.)
3. Enter a unique name for your data validation range, such as MyValRange, then click on OK.
4. Select the cell for which you want to define a validation rule.
5. Choose Validation from the Data menu. Excel displays the Data Validation dialog box. (Click here to see a related figure.)
6. Use the Allow and Data drop-down lists to specify how you want Excel to validate the data. Depending on your selections, you will see a Value, Minimum, or Maximum boxes appear in the dialog box.
7. In the appropriate boxes (Value, Minimum, or Maximum), specify the name you gave your data validation range, in step 3. For instance, you could enter MyValRange.
8. Click on OK.

This approach works great if the data validation range is in the same workbook. What if you want to use a data validation range that is in a different workbook entirely? You can trick Excel into accepting your external reference if, in step 7, you enter a formula such as the following:

=INDIRECT("[Book2]Sheet1!D6")

This formula uses the INDIRECT function to return the value at a cell on another worksheet, and the data validation feature will accept it with no problems. In this case the cell being checked is at cell D6 on Sheet1 of Book2. In order for this to work, you will need to make sure that Book2 is open at the same time that your main workbook is open.