title: Hive Insert Overwrite Table
body: <p>I'm new to Hive and I wanted to know if insert overwrite will overwrite an existing table I have created.
  I want to filter an already created table, let's call it TableA, to only select the rows where age is greater than 18. Can I achieve this using insert overwrite table?</p>
  
  <p>I'm thinking of writing something like:</p>
  
  <pre><code>INSERT OVERWRITE TABLE TableA SELECT a.Age FROM TableA WHERE a.Age &gt; = 18
  </code></pre>
  
  <p>there are NA entries in the table I created, but I assume that after I filter this table there will be no NAs in the Age column, right?</p>