title: How to lower the case of column names of a data frame but not its values?
body: <p>How to lower the case of column names of a data frame but not its values? using RAW Spark SQL and Dataframe methods ?</p>
  
  <p>Input data frame (Imagine I have 100's of  these columns in uppercase)</p>
  
  <pre><code>NAME | COUNTRY | SRC        | CITY       | DEBIT
  ---------------------------------------------
  "foo"| "NZ"    | salary     | "Auckland" | 15.0
  "bar"| "Aus"   | investment | "Melbourne"| 12.5
  </code></pre>
  
  <p>taget dataframe</p>
  
  <pre><code>name | country | src        | city       | debit
  ------------------------------------------------
  "foo"| "NZ"    | salary     | "Auckland" | 15.0
  "bar"| "Aus"   | investment | "Melbourne"| 12.5
  </code></pre>