title: Compare the existing neo4j with a csv and add missing nodes and relationships from a csv
body: <p>Below is my code to create a neo4j relationship by reading from a csv file.</p>
  
  <pre><code>import csv
  from py2neo import neo4j, cypher, authenticate, Graph
  from py2neo import node, rel
  import py2neo
  authenticate("localhost:7474", "neo4j", "bhatt1234")
  graph_db = neo4j.Graph("http://localhost:7474/db/data/")
  ifile = open('agent_send.csv',"rb")
  reader = csv.reader(ifile)
  rownum = 0
  for row in reader:
  colnum = 0
  for col in row:
  rel =  graph_db.merge({))
  rownum += 1
  ifile.close()
  </code></pre>
  
  <p>SO , </p>
  
  <p>I am looking to build a process to do daily imports from a csv to an already exisiting neo 4j. For that I need to use merge() statement. But I am grappling with using merge in py2neo. I need to use the merge between my csv and already existing nodes and relations in my neo4j db.</p>
  
  <pre><code>    :START_ID(Agent),:END_ID(Agent),TXN_KEY,Amount,SendTime,PayTime,:TYPE
         AEX053163,AEX010922,5000000000107593411,20.0,1361439,1362963.0,Agent_Send
  AKJ063072,AS1034942,5000000000108495674,220.0,1361434,1362369.0,Agent_Send
  ADT326742,AMX002998,5000000000106488543,1000.0,1361435,1363053.0,Agent_Send
  ARA031639,AED100363,5000000000106029876,1669.0,1361424,1362506.0,Agent_Send
  AKC403616,ADJ122111,5000000000107872144,180.0,1361415,1362680.0,Agent_Send
  </code></pre>
  
  <p>Above is a CSV which has a relation. So, how do I put this relation under g.merge()?</p>