实现当点击登录界面的登录按钮时，会连接到本地MySQL数据库，根据相应数据表实现登录。
login1.pro
#
# Project created by QtCreator 2022-01-06T22:10:15
#
#-------------------------------------------------
QT += core gui sql
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = login1
TEMPLATE = app
# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS
# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0
SOURCES += main.cpp\
mainwindow.cpp \
logindialog.cpp
HEADERS += mainwindow.h \
logindialog.h
logindialog.h
#ifndef LOGINDIALOG_H
#define LOGINDIALOG_H
#include <QDialog>
#include <QLabel>
#include <QLineEdit>
#include <QSqlDatabase>
#include <QDebug>
#include<QStringList>
#include<QSqlQuery>
class LoginDialog : public QDialog
{
Q_OBJECT
public:
LoginDialog(QWidget *parent = 0);
~LoginDialog();
private:
QLabel *usrLabel;
QLabel *pwdLabel;
QLineEdit *usrLineEdit;
QLineEdit *pwdLineEdit;
QPushButton *LoginBtn;
QPushButton *exitBtn;
private slots:
void login();
void close();
signals:
void signal_username(QString);
};
#endif // LOGINDIALOG_H
logindialog.cpp
关键代码（连接部分）
void LoginDialog::login(){
QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
db.setHostName("localhost");
db.setDatabaseName("scts"); //连接的数据库名字
db.setUserName("root");
db.setPassword("qazqaz12");
if(!db.open()) //通过open连接数据库
qDebug()<<"连接失败";
else qDebug()<<"连接成功";
QString zhanghao = usrLineEdit->text(); //zhanghao和mima是sql中对应表的列名
QString mima = pwdLineEdit->text();
QString s=QString("select * from guanli where zhanghao='%1'and mima='%2' ").arg(zhanghao).arg(mima);
QSqlQuery query(db); //数据库函数的传参
query.exec(s);
if(query.first()){
QMessageBox::information(NULL, "登陆成功", "登陆成功！！！", QMessageBox::Yes);
accept();
}
else
QMessageBox::warning(NULL,"Error","登录失败，请重试！！！");
usrLineEdit->clear();
pwdLineEdit->clear();
usrLineEdit->setFocus();
}
main.cpp
#include "mainwindow.h"
#include <QApplication>
#include "logindialog.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
LoginDialog dlg;
if(dlg.exec()==QDialog::Accepted){
w.show();
}
return a.exec();
}