title: Can a subquery be used with the VALUES keyword?
body: <p>I was under the impression that it could not, but then I ran across these 2 examples (using Oracle XE and SQL Developer):</p>
  
  <p><strong>Example 1</strong> - executes without error</p>
  
  <pre><code>insert into regions (region_id, region_name)
  values ((select max(region_id)+1 from regions), 'Great Britain');
  </code></pre>
  
  <p><strong>Example 2</strong> - returns error (shown below)</p>
  
  <pre><code>insert into regions (region_id, region_name)
  values (select region_id, region_name from regions);
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code>Error starting at line 1 in command:
  insert into regions (region_id, region_name)
  values (select region_id, region_name from regions)
  Error at Command Line:2 Column:9
  Error report:
  SQL Error: ORA-00936: missing expression
  00936. 00000 -  "missing expression"
  *Cause:    
  *Action:
  </code></pre>
  
  <p>So, it appears that there is more to it. Can anyone provide an explanation of under what conditions it is/isn't ok to include subqueries with the <code>VALUES</code> keyword?</p>