Automatic Sequential Numbering of Non-Sequential Items (READ JUN 9 2021 FOLLOW-UP)

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This setup allows Airtable to automatically number collections of items that may not be in sequential order. Item length can be either fixed or variable, with only minor changes needed to the core system to accommodate the latter.

To borrow from the thread that inspired this endeavor, say you’re building product codes that have a variant sub-code, and want that sub-code to automatically increment each time an item of a given product code is added in a new record. However, it needs to auto-increment each product’s sub-code separately, even when product codes are added out of order.

For example, the first product code is 001, and its initial sub-code is 1, so the full combined code is 001-1. When you add a new variation of product 001, the sub-code bumps up by 1, creating 001-2.

Now a new product is introduced with code 002. Because it’s the first of its kind, its full combined code is 002-1. If we then introduce a third variant of product 001, it would end up with a combined code of 001-3.

So far our full product codes, in the order they were created, look like this:


For a small list, creating these manually might not be a problem, but most people don’t use Airtable with small lists. :winking_face: It would be much easier to manage if the variant codes would auto-increment each time we add a new product code.

This independent sequential numbering requires some knowledge of how many of each item came before the current one, no matter how far back in the list those previous items might live. Because each Airtable record is independent, not having any “knowledge” of any other records in the same table, there’s no direct way to reference other records to make this count. However, with a little table and field trickery (inspired by the work of @W_Vann_Hall), this can be done. The core method requires items of a fixed length, but with a minor adjustment it will also work to track items of varying lengths.

Here’s a sample base that you can copy if you wish to dig into the guts of the system, which are described below.

Core Solution
Only two tables are required:

  1. The main table recording the items to be tracked.
  2. A [Control] table with a single record.

The data requirements for this setup are:

  1. The primary field in the main table must be an Autonumber field.
  2. Every record in the main table must be linked to the lone record in the [Control] table.
  3. The character length of the data in the field containing the base items to be tracked must be the same for every record. The exact length isn’t important, but it must be consistent. For example, if you’re going to use a five-character base code, the content of that code can be pretty much anything as long as it’s unique (obviously), and always five characters long in every record. The good news is that the field type can be any number of things, including (but not limited to) Single line text, Single select, Date, Duration, Phone Number, or even a link from another table

Here’s a cropped look at the [Fixed Length] table in the sample base:


Here’s a rundown of how the system works. All field names are from [Fixed Length]:

  • First, a unique character is added to the base item (see the {Unique Base} field), in order to prevent accidental crossover between base items when a SUBSTITUTE is run later in the process. My sample base uses a vertical bar, but anything else can be used instead as long as it’s not part of any of the base codes.
  • These unique items are looked up in the [Control] table, and that collection is then looked up back in the main table (see the {Lookup} field).
  • That lookup is then condensed into a string, and only the leftmost portion kept, with the length based on multiplying the record’s autonumber value by the {Unique Base} length (see the {Truncated} field). For example, if {Unique Base} is four characters long, this field will only keep the first four characters of the mashed-together lookup for the first record. For the second record, it will keep the first eight characters, and so on. This creates a record-by-record tally of everything that has been added.
  • The {Substitute} field then takes that tally and removes all instances of {Unique Base}, leaving everything else except that item.
  • The length of {Substitute} is subtracted from the length of {Truncated}, then divided by the length of {Unique Base}, and we have the unique number to assign to the listed item (see the {Variant} field)
  • The variant number is combined with the base and any desired separators in the {Final} field.

The four helper fields in the main table can be hidden once everything is set up. Because the numbers assigned in the Autonumber field are maintained even when reordering records, the variant numbers remain properly assigned even after records are moved around.

Variable Length Items
The same basic system also works with items of varying lengths. However, because of that variation, we can’t use the items themselves to track their count. Instead, we need to track another fixed-length item that’s tied to that primary item. For this, I created a new table, with the item names in the primary field, an autonumber field adjacent to that, and a formula field that padded the autonumber with leading zeroes to create a unique fixed-length ID for each item. Because these IDs are only going to be used in various formulas, I also added the vertical bar character here instead of doing so in the main table.

Back in the main table, the base items became links to records in that other table, with a lookup field pulling in each item’s unique ID, and then the rest of the system flows as outlined above, operating on that ID instead of the item itself. Once the item’s unique number is calculated, it’s combined with the original item.

Here’s a sample lookup table for this variable-length system (the [Presidents] table in the sample base):


And here’s the main portion of the [Variable Length] table:


60 Replies 60

@Justin_Barrett – terrific work! I’d simultaneously been working on a sequential numbering routine that restarted automatically each day, allowing such things as ‘03/31/2019.1’, ‘03/31/2019.2’, ‘03/31/2019.3’, and so on, but you beat me to the punch. (I went ahead and posted it, anyway — but it appears Discourse can’t easily differentiate between self-deprecating humor and other-deprecating invective [unsurprisingly], so my post awaits moderator approval… .) Your solution is better, though, being more general-purpose.

Edit: A-ha! Here 'tis.

5 - Automation Enthusiast
5 - Automation Enthusiast

Just looked at the example table and this is EXACTLY what we need! Is there any way you would be willing to help me set this up? I’d be happy to share my work e-mail address so we don’t have to keep coming back to this thread.

Thank you! I am so excited about this!

I’d be happy to help you set this up, Sara. Send your email address via PM and we’ll get rolling!

5 - Automation Enthusiast
5 - Automation Enthusiast

@Justin_Barrett I found this show and tell-and it is AMAZING! I made a copy of your base and played with it to make sure it would work if I used dates as the base-and it did. But when I incorporated it into my company’s CRM-it didn’t work :frowning:

Instead of the variant being unique it just states the total number of of records with that date. I have tried recopying the formulas but to no avail.

Would you or someone be willing to take a look at it for me?

Thank you!


Yes, I’d be happy to take a look at it, though I won’t have time to do so until later tomorrow afternoon. I’ll let you know what I found after reviewing what you shared.

5 - Automation Enthusiast
5 - Automation Enthusiast

Thank you! I poked around and noticed that some records are responding as expected while others are not. Which makes it more confusing. The screen shot below shows both cases.


The issue with @Devonna_Wolfe’s base, and with another base that I fixed a while ago, has to do with the autonumber field that’s a required part of the system. I’m not able to edit my original post any more, so I’m adding the relevant details here.

Deleting a record in the main table will break the automatic sequencing of any items after that point. Thankfully there’s a simple fix: Change the autonumber field to a single line text field, save the change, then change it back to autonumber. This will force Airtable to rebuild the numbering sequence, and the sequence numbering will be correct.

The Long Version
When I was initially testing this system, I somehow didn’t think to test how deleting records would affect the calculations. Some of those calculations are based on the number of records in the table, and some are based on the hidden autonumber field that’s integral to the system. In theory those should always stay in sync. However, once a record is deleted, the numbering will be out of sync from that point on. For example, if your main table contains 200 records, but you delete record 90, records 91 onward won’t be synced properly. Thankfully the above fix takes just a few seconds, and will correct the problem.

One way to be alerted automatically when the numbering scheme gets out of sync is to make a field named {Sync} containing the following formula (replacing {Unique Base} with your own field name if necessary):

IF(LEN(Truncated) != Autonumber * LEN({Unique Base}), "❌")
4 - Data Explorer
4 - Data Explorer

I have not been able to get past this step of the system. It seems to break whenever I add the {Unique Base} into the substitute formula in place of the old text variable. This is the formula I am using which results in an error. Is there a different formula that should be used here?

SUBSTITUTE(Truncated,{Unique Base},"")

Welcome to the community, @Weston_Beaumont! :grinning_face_with_big_eyes: That’s the correct formula, assuming that you used those exact names for your fields when building this system in your own base. What kind of error message are you getting? Does Airtable allow you to save that formula, or is the error appearing in the formula field setup dialog?

Note: for the next 48 hours I’ll be largely unable to respond as we drive across the country to our new home. I’ll reply as soon as I can after that.