title: Postgres query to check a string is a number
body: <p>Can anyone tell me the query to check whether a string is a number(double precision). It should return true if the string is number. else it should return false.</p>
  
  <p>consider : </p>
  
  <pre><code>       s1 character varying;
         s2 character varying;
  
         s1 ='12.41212' =&gt; should return true
         s2 = 'Service' =&gt; should return false
  </code></pre>