o MySQL 中抓「出現一次」的個數:
SELECT COUNT(DISTINCT `UsrIp`) FROM mytab;
比較:
SELECT COUNT(DISTINCT `UsrIp`) FROM mytab GROUP BY `UsrIp`;
o MySQL 中抓「出現一次」的個數:
SELECT COUNT(DISTINCT `UsrIp`) FROM mytab;
比較:
SELECT COUNT(DISTINCT `UsrIp`) FROM mytab GROUP BY `UsrIp`;