带头尾指针的list，可以使用任意数据类型替换例子中的类型，实现从尾部插入元素，从任意位置删除元素。-lead the list tail pointer can be used to replace arbitrary data types examples of types, from a tail insert elements from any location delete elements.
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.003875s ]
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:0.077005s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001075s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001136s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.000961s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003114s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000808s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003636s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.015105s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001083s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 264087 [ RunTime:0.016578s ]
