摘要:
1、tomcat context.xml 参考配置: <?xml version="1.0" encoding="UTF-8"?> <Context> <!-- Default set of monitored resources. If one of these changes, the --> 阅读全文
摘要:
将 SELECT id FROM table ORDER BY RAND() LIMIT n; 优化为: SELECT id FROM table t1 JOIN (SELECT RAND() * (SELECT MAX(id) FROM table) AS nid) t2 ON t1.id > t 阅读全文