title: Column names containing dots in Spectrum
body: <p>I created a customers table with columns has account_id.cust_id, account_id.ord_id and so on. 
  My create external table query was as follows:</p>
  
  <pre><code>CREATE EXTERNAL TABLE spectrum.customers
  (
  "account_id.cust_id" numeric,
  "account_id.ord_id" numeric
  ) 
  row format delimited
  fields terminated by '^'
  stored as textfile
  location 's3://awsbucketname/test/';
  
  SELECT "account_id.cust_id" FROM spectrum.customers limit 100 
  </code></pre>
  
  <p>and I get an error as :</p>
  
  <blockquote>
    <p>Invalid Operation: column account_id.cust_id does not exists in
    customers.</p>
  </blockquote>
  
  <p>Is there any way or syntax to write column names like account_id.cust_id (text.text) while creating the table or while writing the select query? </p>
  
  <p>Please help. </p>
  
  <p>PS: Single quotes, back ticks don't work either.</p>