title: database query in c++
body: <pre><code>query &lt;&lt; "SELECT DISTINCT \"internalIP\", COUNT(DISTINCT \"externalIP\"), "
      &lt;&lt; "SUM(\"numBytes\"), SUM(\"content\") FROM \""
      &lt;&lt; NON_DNS_TRAFFIC_SCHEMA_NAME &lt;&lt; "\".\"" &lt;&lt; date
      &lt;&lt; "\" GROUP BY \"internalIP\"";
  result = PQexecParams(postgreSQL, query.str().c_str(), 0, NULL, NULL, NULL, NULL, 1);
  </code></pre>
  
  <p>What does this query means? Also Any idea about function <code>PQexecParams()</code>?</p>