enforce unique value in a lookup field in sharepoint lists

Question

enforce unique value in a lookup field in sharepoint lists

Anonymous

In Sharepoint Lists, I have a 'client name' field that I would like to enforce unique values. It is a look up column. It looks up a calculated, concatenated field from the client details List. How do I do this?

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3 answers

Answer 1

Hi Emily Allan,
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Tue - H - MSFT | Microsoft Community Support Specialist

Answer 2

Anonymous

Hi @Emily Allan

You can create the calculated column with and concatenate the Internal Item Id and lookup field value to the calculated field it will always generate unique value every time
eg Client_Name_ItemId, test_1

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Answer 3

Hi Emily Allan

I am happy to help you with your questions.
As my understanding, you try to create a lookup column, based on data from columns from client details List. I would suggest creating a calculated column with a unique validation constraint, then create a lookup column based on the calculated column. My approach would be:

Creating Calculate Column (SharePoint > List > Add column > See all column types > Next > Calculated)
In create calculate column screen, you can set the default formula for column value.
Click on the Column Validation, it will expand, and you can set validation formula in there. Follow instruction from Examples of common formulas in lists - Microsoft Support
After that create your lookup column, reference to the newly created calculated column.

From there, whenever new item added in client detail, new item with lookup column will appear. Let me know if there some misunderstand with my approach. I may not solve this within first reply, but I hope I can open new approach and help you come up with a solution.

Sincerely,
Tue -H - MSFT | Microsoft Community Support Specialist