title: How to handle white spaces in dataframe column names in spark
body: <p>I registered a tmp table from a df that has white spaces in the column header.how can i extract the column while using sql query via sqlContext.
  I tried to use back-tick but it is not working</p>
  
  <pre><code>df1 =  sqlContext.sql("""select Company, Sector, Industry, `Altman Z-score as Z_Score` from tmp1 """)
  </code></pre>