title: Need help to capture part of string value using particular delimiter function in Vertica
body: <p>I have a <code>CustomerKey</code> table which consists of a column <code>Key</code> which has sample value like below:</p>
  <pre><code>ar.system.company.addr.clearinghouse
  ar.system.company.addr.dtac.th
  ar.system.company.info.clearinghouse.th
  .......... ...         ......
  ar.system.company.addr.dtac
  ar.system.company.addr.paysbuy
  </code></pre>
  <p>Now I have to use  one function, which return the value up to the 4th delimiter <code>.</code>.</p>
  <p>Like:</p>
  <pre><code>ar.system.company.addr
  ar.system.company.addr
  ..... ... .....
  ar.system.company.addr
  </code></pre>
  <p>N.B: I have found one similar kind of function <code>STRTOK()</code> which is used in Snowflake. But I did not find any function like this in Vertica.</p>