title: How to select group by with Regex
body: <p>I've a table with the columns: <code>itime, service, count</code>.</p>
  <p>I can write such a SQL to query some result:</p>
  <pre><code>SELECT
      toUnixTimestamp(toStartOfMinute(itime)) * 1000 as t,
      service,
      sum(count)
  FROM myTable
  WHERE
      -- aaa and bbb are two integers
      itime BETWEEN toDateTime(aaa) AND toDateTime(bbb)
      and service like 'mySvr_%'
  GROUP BY
      service,
      t
  ORDER BY t
  </code></pre>
  <p>It works as expected.</p>
  <p>For the column <code>service</code>, the contents always start with <code>mySvr_</code>, such as <code>mySvr_101</code>, <code>mySvr_102</code>, <code>mySvr_201</code>, <code>mySvr_202</code>.</p>
  <p>Now, I want to <code>group by</code> the <code>service</code> with some regular expression so that the result will be <code>group by</code> like this: <code>mySvr_1xx</code>, <code>mySvr_2xx</code>, <code>mySvr_3xx</code> etc.</p>
  <p>But I don't know how. Could someone help me?</p>