title: How to create table from SELECT statement in oracle 11g
body: <p>I want to CREATE table from another table 
  I tried below code</p>
  
  <pre><code>CREATE TABLE AS tbl_01
  As
  SELECT a.col1 c1, a.col2 c2, MAX(a.col3 c3)
  FROM tbl a
  WHERE flag= 2
  GROUP BY col1, col2
  </code></pre>
  
  <p>This query run, but When I am going to expand column in datatabse explorer it gives error <code>Conversion from type DBNULL to type Integer is not valid</code></p>