As their knowledge increase, most Excel users follow a number of natural evolutionary steps when working with data validation lists. The start is to create a simple validation list by entering a comma separated list of valid inputs in the Source box of the Data Validation dialogue.

The next step on the ladder is to enter a range address as the Source (or select a range by clicking on the range selector).

At some point after this users want to use a Source range that is on a different sheet from the cells they want to apply the validation to. When they try to select the Source range using the range selector Excel prevents them from selecting a range on a different sheet, so the range address has to be entered manually, for example “=’My sheet’!$B$3:$B$5”. After a while they realise what a pain it is to do all this manual typing of range addresses, and turn to using named ranges. Simply name the Source range, say “MyListSource”, and use the name as the data validation source.

But what if you want to add a new item to your validation list? The simple way to do this is to change your named range so that it includes a new cell (in other words change the “RefersTo” property to “=’My sheet’!$B$3:$B$6”). A better way of doing it is by making sure that your named range automatically includes the new cell, by creating a dynamic named range (technically named formula is a better description). This is done by putting something like this in the RefersTo box for the named range:

“=OFFSET(’My sheet’!$B$3,0,0,COUNTA(’My sheet’!$B:$B),1)”

I don’t want to go into the details of this here, but if you don’t understand how this works then a simple search for “Excel Dynamic Named Ranges” should turn up ample reference material.

Dynamic named ranges work well for creating a dynamic data validation list, but there are three drawbacks to using them:

1. They require some effort to set up

2. It is not transparent and it can be difficult for someone else to figure out how it works

3. If any entries are made in column B that are not part of the validation list then the dynamic named range won’t be accurate

Three quick steps

So finally we get to the raison d’etre for this article: how to use a table to quickly and easily create a dynamic data validation list.

Step 1: Create the table containing the list of valid entries. Give the table a name.

Step 2: Create a named range, say “MyListSource”. In the RefersTo box, enter the name of the table you’ve just created (“tblSourceList” in my example above).

Step 3: Apply the data validation by entering “=MyListSource” as the data validation Source.

Voila! Now you can simply add entries to the table and they will automatically become valid entries in your data validation list.

Step 1: Create the file in Excel

Save the workbook somewhere in a local or network folder. There are certain limitations that apply to the kind of workbook you can embed, for example it can not contain macros or data validation.

Step 2: Create a Skydrive account

If you don’t already have one, all you need to use Skydrive is a Windows Live ID.

Step 3: Upload the file to Skydrive

When you are logged in to Skydrive, click “Add files” and follow the instructions to upload your workbook.

Step 4: Generate the HTML code

In Skydrive, navigate to the file you have uploaded and select it by ticking the box to the left of it. On the right hand sidebar, click “Embed”. A new window appears containing a preview of your workbook, and on the right hand side a box containing the HTML iFrame tag you need. You can copy it as it appears there, or click on “Customize this embedded Excel workbook” at the bottom right to select some options. For example you can choose to display only a part of the workbook, allow or disallow downloading the workbook, set Interaction permissions and so on.

Step 5: Paste the code into your web page

Either give the iFrame code to your web administrator, or if you know what you are doing simply paste it into the HTML code of your website or blog.

There you have it. Below is an example of a simple loan repayment calculator.

If your sales data is in a table with the same layout in each of the sheets, then a simple formula can be used to calculate the total for any cell in the table. For the sample above: =SUM(‘Boston:Tokyo’!C3). This formula can be entered in any cell in your workbook except in cell C3 in a sheet between Boston and Tokyo (in which case a circular reference will occur). Usually when you want to sum across sheets like this you will create a new sheet, named “Total Sales” say, to the right or left of the sheets you want to sum across. You can then copy the table from one of the sheets to your “Total Sales” sheet and replace the (non-label) values with a SUM formula as above. The formula can be copied/dragged as for any other formula, with the normal rules of absolute/relative references applying. You can also replace the SUM formula with AVERAGE, MAX, MIN, COUNT, COUNTA and so forth to calculate different quantities.

It may be that the sheets you want to sum across are not arranged contiguously. This presents no problem as you can some over multiple series of sheets by separating each series by a comma, for example =SUM(‘Boston:Chicago!C3,’Moscow:Tokyo’!C3). You also don’t need to some over the same cell – it may be that data in column C for North American locations correspond to data in column D for Asian locations. In that case you can use =SUM(‘BostonChicago!C3,’ Moscow:Tokyo’!D3).

But what happens if you want to add a new sheet and include it in your total? For example, a new sales location may have opened in Europe, or a new month of sales data becomes available. If the new sheet lies between the first and last sheet (alphabetically or chronologically or otherwise) that are summed then it can simply be copied, moved or dragged to a position between the two. No changes to the SUM formulas will have to be made and the values in the new sheet will automatically be included in the totals. However if, for example, you needed to add “Vietnam” as a sales location in our example and you want to arrange your sheets alphabetically, then Vietnam becomes the last sheet that you need to sum across. In this case the formulas will have to be changed from =SUM(‘Boston:Tokyo’!C3) to =SUM(‘Boston:Vietnam’!C3). And if this happens frequently, for example if you add a new sheet monthly, then your SUM formulas will require a lot of maintenance.

The solution is to add blank sheets to the left and right of the sheets you want to sum across to form a “pocket”, as below.

The formula then becomes =SUM(‘SalesStart:SalesEnd’!C3) and you can drag new sheets into the pocket as often as you like without having to update the formulas. You can also use this method to create totals for sub-categories, for example you can add blank sheets named AsiaStart and AsiaEnd and so forth, in the obvious manner.