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:0.001108s ]
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:0.094729s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.000875s ]
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SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001143s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003149s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000800s ]
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SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.015935s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001586s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 49141 [ RunTime:0.020491s ]
