Auto number column in SharePoint list

Question

In a SharePoint list I want an auto number column that as I add to the list gets incremented. How best can I go about this?

Answer 1

Sharepoint Lists automatically have an column with "ID" which auto increments. You simply need to select this column from the "modify view" screen to view it.

Answer 2

I had this issue with a custom list and while it's not possible to use the auto-generated ID column to create a calculated column, it is possible to use a workflow to do the heavy lifting.

I created a new workflow variable of type Number and set it to be the value of the ID column in the current item. Then it's simply a matter of calculating the custom column value and setting it - in my case I just needed the numbering to begin at 100,000.

Answer 3

If you want something beyond the ID column that's there in all lists, you're probably going to have to resort to an Event Receiver on the list that "calculates" what the value of your unique identified should be or using a custom field type that has the required logic embedded in this. Unfortunately, both of these options will require writing and deploying custom code to the server and deploying assemblies to the GAC, which can be frowned upon in environments where you don't have complete control over the servers.

If you don't need the unique identifier to show up immediately, you could probably generate it via a workflow (either with SharePoint Designer or a custom WF workflow built in Visual Studio).

Unfortunately, calculated columns, which seem like an obvious solution, won't work for this purpose because the ID is not yet assigned when the calculation is attempted. If you go in after the fact and edit the item, the calculation may achieve what you want, but on initial creation of a new item it will not be calculated correctly.

Answer 4

So I am not sure I can really think of why you would actually need a "site collection unique" id, so maybe you can comment and let us know what is actually trying to be accomplished here...

Either way, all items have a UniqueID property that is a GUID if you really need it: http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.splistitem.uniqueid.aspx

Answer 5

As stated, all objects in sharepoint contain some sort of unique identifier (often an integer based counter for list items, and GUIDs for lists).

That said, there is also a feature available at http://www.codeplex.com/features called "Unique Column Policy", designed to add an other column with a unique value. A complete writeup is available at http://scothillier.spaces.live.com/blog/cns!8F5DEA8AEA9E6FBB!293.entry

Answer 6

You can't add a new unique auto-generated ID to a SharePoint list, but there already is one there! If you edit the "All Items" view you will see a list of columns that do not have the display option checked.

There are quite a few of these columns that exist but that are never displayed, like "Created By" and "Created". These fields are used within SharePoint, but they are not displayed by default so as not to clutter up the display. You can't edit these fields, but you can display them to the user. if you check the "Display" box beside the ID field you will get a unique and auto-generated ID field displayed in your list.

Check out: Unique ID in SharePoint list