人们在使用SQL时往往会陷入一个误区，即太关注于所得的结果是否正确，而忽略了不同的实现方法之间可能存在的 性能差异，这种性能差异在大型的或是复杂的数据库环
-people in the use of SQL often mired in a dangerous zone, that is too interested in the results is correct, neglect of different implementations may exist between the performance difference This difference in the performance of large or complex database Central
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.002031s ]
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:0.088649s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.002312s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001956s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.002512s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.004029s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.002438s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003446s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.015214s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.002784s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 150683 [ RunTime:0.001164s ]
