title: Pandas: Join dataframes on selected columns
body: <p>I have two data frames as following </p>
  
  <pre><code> Data Set A
   ID type   msg 
   1  High   Lets do
   2  Low    whats it 
   3  Medium thats it
  
   Data Set B 
   ID  Accounttype
   2   Facebook
   3   Linkedin
  </code></pre>
  
  <p>How can I get an updated table with help of join in pandas, it should look like 
   an </p>
  
  <pre><code>Updated DatasetA 
  
  ID Account    type  msg
   1            High   Lets do
   2  Facebook  Low    whats it 
   3  Linkedin  Medium thats it
  </code></pre>
  
  <p>I can easily do it in SQL with Update and inner join, how to perform it in pandas, I tried to do it, but most of the operations for append/ merge. Any help will be appreciated</p>