Properties beforeproperties itemupdating
Post 1 : Synergy Online In this post Randy Williams, provided clear explanation about this.
Some basic details about Event Receivers got from this post Event receivers are a great way to hook into various Share Point events.
After Properties[internal Name]); if (Before Value !
Before Properties[internal Name]); string After Value = properties.
In my case after specifying the event receiver as Synchronous I was able to compare existing values with values in properties.
(no updates required since you are changing the value before it gets saved) I would verify that your Event Receiver is attached to the list.Here Randy Williams denoted Before Properties of SPEvent Receiver contains "No Value" for lists. So its good and I got better idea of how before and after events work for both lists and libraries from this post.But i didn't stop my analyze on this, i continue with few more posts, then i identified following post Post 2 : Note : This is untested one, check at your end once before implementing in production.These properties are used to get previous values and the current value in the event receiver events.Learn about before properties afterproperties itemupdated in Share Point 2013.