title: SQLalchemy rowcount always -1 for statements
body: <p>I was playing around with SQLalchemy and Microsoft SQL Server to get a hang of the functions when I came across a strange behavior. I was taught that the attribute rowcount on the result proxy object will tell how many rows were effected by executing a statement. However, when I select or insert single or multiple rows in my test database, I always get -1. How could this be and how can I fix this to reflect the reality?</p>
  <pre><code>connection = engine.connect()
  metadata = MetaData()
  
  # Ex1: select statement for all values
  student = Table('student', metadata, autoload=True, autoload_with=engine)
  stmt = select([student])
  result_proxy = connection.execute(stmt)
  results = result_proxy.fetchall()
  print(result_proxy.rowcount)
  
  # Ex2: inserting single values
  stmt = insert(student).values(firstname='Severus', lastname='Snape')
  result_proxy = connection.execute(stmt)
  print(result_proxy.rowcout)
   
  # Ex3: inserting multiple values 
  stmt = insert(student)
  values_list = [{'firstname': 'Rubius', 'lastname': 'Hagrid'},
                 {'firstname': 'Minerva', 'lastname': 'McGonogall'}]
  result_proxy = connection.execute(stmt, values_list)
  print(result_proxy.rowcount)
  </code></pre>
  <p>The print function for each block seperately run example code prints -1. The Ex1 successfully fetches all rows and both insert statements successfully write the data to the database.</p>
  <p>According to the following issue, the rowcount attribute isn't always to be trusted. Is that true here as well? And when, how can I compensate with a Count statement in a SQLalcehmy transaction?
  <a href="https://stackoverflow.com/questions/27363413/pdorowcount-returning-1">PDO::rowCount() returning -1</a></p>