title: AWS Athena json_extract query from string field returns empty values
body: <p>I have a table in athena with this structure</p>
  
  <pre><code>CREATE EXTERNAL TABLE `json_test`(
    `col0` string , 
    `col1` string , 
    `col2` string , 
    `col3` string , 
    `col4` string , 
    )
  ROW FORMAT SERDE 
    'org.apache.hadoop.hive.serde2.OpenCSVSerde' 
  WITH SERDEPROPERTIES ( 
    'quoteChar'='\"', 
    'separatorChar'='\;') 
  </code></pre>
  
  <p>A Json String like this is stored in "col4":</p>
  
  <pre><code>{'email': 'test_email@test_email.com', 'name': 'Andrew', 'surname': 'Test Test'}
  </code></pre>
  
  <p>I´m trying to make a json_extract query:</p>
  
  <pre><code>SELECT json_extract(col4 , '$.email') as email FROM "default"."json_test"
  </code></pre>
  
  <p>But the query returns empty values.</p>
  
  <p>Any help would be appreciated.</p>