我们设计的数据库系统能够实现学生信息管理，学生成绩管理等功能。我们研究了数据库的查询优化问题。-we design a database system to achieve student information management, student performance management capabilities. We have studied the database query optimization problem.
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001124s ]
SELECT `a`.`aid`,`a`.`title`,`a`.`create_time`,`m`.`username` FROM `jrk_downrecords` `a` INNER JOIN `jrk_member` `m` ON `a`.`uid`=`m`.`id` WHERE `a`.`status` = 1 GROUP BY `a`.`aid` ORDER BY `a`.`create_time` DESC LIMIT 10 [ RunTime:0.109823s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001025s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001145s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001032s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003250s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000941s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.005699s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.017526s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001171s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 286500 [ RunTime:0.012843s ]
