考虑到DCT变换中的系数要重复计算，可使用查找表来提高运行的效率，只要开始DCT变换之前计算一次，DCT变换中就可以只查找而无需计算系数。-to the DCT coefficients to be calculated, the use of look-up tables to improve operational efficiency, as long as the DCT started once before, on DCT can only search without calculation of the coefficient.
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001403s ]
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:0.096019s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.000989s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001228s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001006s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.002922s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000877s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003529s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.013713s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001021s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 188211 [ RunTime:0.014540s ]
