Update List Items without modifing System columns in Sharepoint

Its most common we need to update few column values in backed without changing system columns like Modified By, Modified On in a Sharepoint list / document library.

In order to achieve this, we need to go with Item.SystemUpdate() instead of Item.Update() in your C# code.

In case, if its a one time activity and we need to update data in bulk, the easiest way is to go with PowerShell script. Below is the example to update a column value in a list without changing Modified On and Modified By values, using PowerShell.

 Add-PSSnapin microsoft.sharepoint.powershell  
 $web = Get-SPWeb "<<Site URL>>"  
 $list = $web.lists["<<List Name>>"]  
 #Get all items in particular list and save them to a variable.   
 #Here you can also apply your CAML query to fetch particular set of records  
 $items = $list.items  
 #Go through all list items  
 foreach($item in $items)  
 {       
      #If any conditions are required, can set them here in if clause.  
      #Update the fields as below.  
      $item["<<Field Display Name>>"] = "<<Value>>";  
      #This is the important change, using systemupdate will just set the above fields.  
      #This will not update Modified & Modified By Fields.  
      $item.SystemUpdate();  
 }  
 $web.Dispose();