How to enforce unique value for a column in SharePoint 2010 using powershell

In this article we will be seeing how to enforce unique value for a list or library column in SharePoint 2010 using C# and powershell.

In SharePoint 2010 we can enforce uniqueness on values in a list or library column, effectively creating a primary key. When you create a column in the list or library you could see an option "Enforce Unique Values" where you can enforce uniqueness. When you enforce uniqueness on a Lookup column, the list item in the target list can have only one list item looking up to it from the child list.

Using C#:

a. Open Visual Studio 2010.

b. Create Console application.

c. Replace the code with the following.

  1. using System;

  2. using System.Collections.Generic;

  3. using System.Linq;

  4. using System.Text;

  5. using Microsoft.SharePoint;

  6. namespace EnforceUniqueValue

  7. {

  8. class Program   

  9. {

  10. static void Main(string[] args)       

  11. {

  12. using (SPSite site = new SPSite("