用java实现电工上的矩形波合成演示，可以清楚的看到合成的变化过程。-Using java to achieve the rectangular electrical wave synthetic presentation, you can clearly see the synthetic process of change.
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001174s ]
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:0.084627s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001136s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001898s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001146s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003605s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.001035s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003165s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.014269s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001265s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 49141 [ RunTime:0.001179s ]
