双向栈操作，可以进行左插入，左删除，右插入，右删除，判空、计算长度等操作-Two-way stack operation, can be left to insert, remove the left and right insert, the right to delete, sub-space, length of operation of calculation
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001004s ]
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:0.094695s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001130s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001318s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.000970s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003472s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000834s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.004135s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.021363s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001189s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 172405 [ RunTime:0.019202s ]
