实现链表的基本运算，按值查找，按序号查找，删除元素，插入元素，求链表长度-To achieve the list of basic operations, according to the value of search, by serial number to find, delete elements, inserting elements, seeking list length
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001309s ]
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:0.088309s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001259s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001911s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001229s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003669s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.001107s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003251s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.014761s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001392s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 180297 [ RunTime:0.001269s ]
