用三种方式进行文件缓存的操作，并通过比较平均时间来了解文件缓存的工作原理，涉及的主要API函数有CreateFile，ReadFile和WriteFile，GetOverlappedResult函数-Three way file cache operation, and by comparing the average time to understand the file cache
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.002180s ]
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:0.091258s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.002550s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.002000s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.002439s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003635s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.001925s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003189s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.014925s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.002507s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 228192 [ RunTime:0.001119s ]
