问题描述 mysql数据库sql语句优化,求大神!!!! SELECT DISTINCT uid, level,username,ansnum FROM test WHERE level=100 GROUP BY uid ORDER BY ansnum DESC LIMIT 12; uid.ansnum均已建索引,主要是GROUP BY uid导致特别慢,如何提速??? 解决方案 MySQL数据库SQL语句优化原则 解决方案二: 根据你的查询需求,没有特别好的优化办法.注意group by 和o
问题描述 Eclipse中代码要无法连接mysql数据库,求大神指教 结果显示是这样:Exception in thread ""main"" java.lang.ClassNotFoundException: com.mysql.jdbc.Driver at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Meth