title: Perl -check for uninitialized value
body: <p>I am doing the below in a perl script:</p>
  
  <pre><code>my @pm1_CS_missing_months = `sqlplus -s $connstr \@DLmissing_months.sql`;
  </code></pre>
  
  <p>it takes the output of an sql query.
  if i have to check for no rows selected,how could i do it?
  i want to do like this:</p>
  
  <pre><code>if(no rows selected)
  {
  do this;
  }
  </code></pre>