基于qt和mysql的学生注册系统（二）

接下来是connection.h头文件，主要用于建立数据库连接：

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   #ifndef CONNECTION_H
  
#define CONNECTION_H
  
#include <QMessageBox>
  
#include <QSqlDatabase>
  
#include <QSqlQuery>
  
#include <QtSql>
  
#include <QVector>
  
#include <QString>
  
#include <mainwindow.h>
  
static bool createConnection()
  
{
  
    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
  
    db.setHostName("localhost");
  
    db.setDatabaseName("Enroll");
  
    db.setUserName("root");
  
    db.setPassword("1");
  
    qDebug() <<"hell";
  
    if(!db.open())
  
    {
  
        QMessageBox::critical(0, qApp->tr("Cannot open database"),
  
            qApp->tr("Unable to establish a database connection."
  
                     ), QMessageBox::Cancel);
  
        return false;
  
    }
  
    // test the connection
  
    QSqlQuery query;
  
    query.exec("SELECT a FROM Student");
  
    qDebug() <<query.size();
  
    while(query.next())
  
    {
  
        QString id = query.value(0).toString();
  
        QString type = query.value(1).toString();
  
        QString data = query.value(2).toString();
  
        qDebug() << id << ", " << type << ", " << data <<endl;
  
         qDebug() <<query.size();
  
    }
  
}
  
#endif // CONNECTION_H
  然后是login类：

我的做法是从对话框读取用户名和密码，用于登录数据库。

头文件：

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   #ifndef LOGIN_H
  
#define LOGIN_H
  
#include <QWidget>
  
#include <QLineEdit>
  
#include <QLabel>
  
#include <QDialogButtonBox>
  
#include <QGridLayout>
  
#include <QDialog>
  
#include <QMessageBox>
  
class login : public QDialog
  
{
  
    Q_OBJECT
  
public:
  
    explicit login(QWidget *parent = 0);
  
signals:
  
public slots:
  
    void accept();
  
private:
  
    QLineEdit *usrEdit;
  
    QLineEdit *pwdEdit;
  
    QLabel *usrLabel;
  
    QLabel *pwdLabel;
  
    QDialogButtonBox *buttonBox;
  
    QGridLayout *grid;
  
};
  
#endif // LOGIN_H
  cpp文件：  
   
  

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   #include "login.h"
  
login::login(QWidget *parent) :
  
    QDialog(parent)
  
{
  
    this->usrLabel=new QLabel(tr("UserName:"));
  
    this->pwdLabel=new QLabel(tr("PassWord:"));
  
    this->usrEdit=new QLineEdit;
  
    this->pwdEdit=new QLineEdit;
  
    pwdEdit->setEchoMode(QLineEdit::Password);
  
    this->buttonBox= new QDialogButtonBox(QDialogButtonBox::Ok
  
                                          | QDialogButtonBox::Cancel);
  
    connect(buttonBox, SIGNAL(accepted()), this, SLOT(accept()));
  
    connect(buttonBox, SIGNAL(rejected()), this, SLOT(reject()));
  
    grid=new QGridLayout;
  
    grid->addWidget(usrLabel,0,0);
  
    grid->addWidget(usrEdit,0,1);
  
    grid->addWidget(pwdLabel,1,0);
  
    grid->addWidget(pwdEdit,1,1);
  
    grid->addWidget(buttonBox,2,1);
  
    this->setWindowTitle("Login");
  
    resize(100,200);
  
    this->setLayout(grid);
  
}
  
void login::accept()
  
{
  
    if(usrEdit->text()=="root"&&pwdEdit->text()=="1")
  
    {
  
    QDialog::accept();
  
    }
  
    else
  
    {
  
        QMessageBox::warning(this,tr("Warning"),tr("Error"),QMessageBox::Yes);
  
        usrEdit->clear();
  
        pwdEdit->clear();
  
        usrEdit->setFocus();
  
    }
  
}
  下篇文章贴关于实现sql语句的几个类。