I need a clarification when we are updating relationship can we get the list of nodes that where affected by that updation. And how to compare the data before and after updation of relationships using cypher query.
If you are executing the query, you can keep track of what you changed. If you want something that happens anytime a change is made from any query, you could use an apoc trigger to run for any change and log the ones you're interested in. The trigger will give you access to the information you want.