some cleanup of request for comments. Work in progress.

Noticed a flaw when fetching the last submission, which is caused by timezone differences. First step to solve this.
Existing Request for Comments still need to be updated with their current submissionId, the SQL to do that is not yet finished.

app/models/request_for_comment.rb

@@ -25,6 +25,35 @@ class RequestForComment < ActiveRecord::Base
             limit 1").first
   end
 
+  def last_submission_before_creation
+    submission1 = Submission.find_by_sql(" select * from submissions
+            where exercise_id = #{exercise_id} AND
+            user_id =  #{user_id} AND
+            '#{created_at.localtime}' > created_at
+            order by created_at desc
+            limit 1").first
+    submission2 = Submission.find_by_sql(" select * from submissions
+            where exercise_id = #{exercise_id} AND
+            user_id =  #{user_id} AND
+            '#{created_at}' > created_at
+            order by created_at desc
+            limit 1").first
+    submission3 = Submission.find_by_sql(" select * from submissions
+            where exercise_id = #{exercise_id} AND
+            user_id =  #{user_id} AND
+            '#{created_at.strftime('%Y-%m-%d %H:%M:%S.%N')}' > created_at
+            order by created_at desc
+            limit 1").first
+    submission4 = Submission.find_by_sql(" select * from submissions
+            where exercise_id = #{exercise_id} AND
+            user_id =  #{user_id} AND
+            '#{created_at.localtime.strftime('%Y-%m-%d %H:%M:%S.%N')}' > created_at
+            order by created_at desc
+            limit 1").first
+    binding.pry
+    submission1
+  end
+
   def comments_count
     submission.files.map { |file| file.comments.size}.sum
   end