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源码下载地址：

http://download.csdn.net/download/qq78442761/9971770

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用SQLyog查看如下图所示：

数据库涉及3个表的构建下面是相关代码。

ER图如下所示：

下面是上课和下课打卡的流程图：

左图为上课，右图为下课

具体代码如下：

DROP TABLE IF EXISTS `subject`;CREATE TABLE `subject` (`id` int(11) NOT NULL,`name` varchar(50) COLLATE utf8_unicode_ci NOT NULL,`time_from` time NOT NULL,`time_to` time NOT NULL,PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;CREATE TABLE `student` (`CardNum` int(11) NOT NULL,`id` int(11) NOT NULL,`class` int(11) NOT NULL,`name` varchar(50) COLLATE utf8_unicode_ci NOT NULL,PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;CREATE TABLE `chose` (`subject_id` int(11) NOT NULL,`student_id` int(11) NOT NULL,`in_num` int(11) NOT NULL,`out_num` int(11) NOT NULL,KEY `Stu_id` (`student_id`),KEY `Sub_id` (`subject_id`),CONSTRAINT `Stu_id` FOREIGN KEY (`student_id`) REFERENCES `student` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,CONSTRAINT `Sub_id` FOREIGN KEY (`subject_id`) REFERENCES `subject` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

下面是一些简单的SQL语句，都插入到Qt程序里面了：

//上课打卡时：查询选课表中是否有此人
select * from student where id in (select student_id from chose
where student_id =(select id from Student where CardNum=0110 and subject_id=(select id from subject where now()>=time_from and now()<=time_to)));
如果有就：
update chose set in_num=in_num+1 where student_id=XXXXXXXX;//下课打卡时：查询选课表中是否有此人
select * from student where id in (select student_id from chose
where student_id =(select id from Student where CardNum=0110 and subject_id=(select id from subject where now()>time_to)));
如果有就
update chose set out_num=in_num+1 where student_id=XXXXXXXX;//根据学号查询对应学号所有课程的出勤信息
select student.id,subject.name,chose.in_num from student,chose,subject where chose.student_id=14220307 and student.id=14220307//根据姓名查询对应学号所有课程的出勤信息
SELECT student.name,subject.name,chose.in_num FROM student,chose,SUBJECT WHERE chose.student_id = (SELECT id FROM student WHERE NAME='张三') AND student.id=(SELECT id FROM student WHERE NAME='张三');//查询选取了此课表的所有出勤人信息,和出勤分数：
select subject.id,subject.name,student.id,student.name,chose.in_num,chose.in_num*10 as '出勤分数'from subject,student,chose where subject.id=chose.subject_id and chose.student_id=student.id;//更具学号删除学生数据
delete from student where id=14220310;//添加学生
insert into student values(9999,14220388,142203,'小白');

这里我们说以下用Qt连接数据库，这里只提供关键代码：

QStringAndBool ConnMysql::LinkMySQL()
{db=QSqlDatabase::addDatabase("QMYSQL");db.setHostName("localhost");db.setDatabaseName(m_DataBase);db.setUserName(m_UserName);db.setPassword(m_PassWd);QStringAndBool returnValues;if(!db.open()){QMessageBox::information(NULL,"提示","数据库连接失败！");returnValues.MesQString="数据库连接失败！";returnValues.MesBool=0;return returnValues;}else{QMessageBox::information(NULL,"提示","数据库连接成功！",QMessageBox::Ok);returnValues.MesQString="数据库连接成功！";returnValues.MesBool=1;return returnValues;}
}void ConnMysql::DisLinkMysql()
{QString SqlQuery="exit";model->setQuery(SqlQuery);}

注意：具体代码在本博文开头，此处只有关键代码；

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