目录

开发环境

  • mysql5.0
  • qt5.8

开发过程

mysql数据库部分

qt开发部分

出现的问题及修复

开发环境

  • mysql5.0
  • qt5.8

开发过程

mysql数据库部分

开启

连接

在mysql中新建数据库

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CREATE DATABASE login_test DEFAULT CHARSET utf8;

选择数据库login_test

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use login_test;

新建表格user_login

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CREATE TABLE user_login
(
 user_id int PRIMARY KEY AUTO_INCREMENT, 
 user_name varchar(60) NOT NULL, 
 user_pwd varchar(60) NOT NULL, 
 user_datetime datetime NOT NULL
);

qt开发部分

新建qt项目,命名为login_test

需要实现的功能

  • 初始化数据库
  • 用户注册
  • 用户登录

初始化数据库函数

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void Widget::InitDatabase()
{
    qDebug() << "Init database";
    m_DB = QSqlDatabase::addDatabase("QMYSQL");
    m_DB.setHostName("localhost");
    m_DB.setDatabaseName("login_test");
    m_DB.setUserName("root");
    m_DB.setPassword("123456");
    if (!m_DB.open())
    {
         qDebug() << "open error";
         ui->user_login->setEnabled(false);
         ui->user_register->setEnabled(false);
         return;
    }
    qDebug() << "open ok";
}

用户注册函数

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void Widget::on_user_register_clicked()
{
    QString strName = ui->user_name->text();
    QString strPwd = ui->user_pwd->text();
    qDebug() << strName << " " << strPwd;
    if (strName.length() == 0 || strPwd.length() == 0)
    {
        qDebug() << "user name or pwd error";
        return ;
    }
    QString strSql = "insert into user_login (user_name, user_pwd, user_datetime) values ('" + strName
                     + "','" + strPwd + "', now())";
    qDebug() << strSql;
    QSqlQuery query(m_DB);
    if (!query.exec(strSql))
    {
        qDebug() << "sql exec error";
        return;
    }
    qDebug() << "register ok";
}

用户登录

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void Widget::on_user_login_clicked()
{
    QString strName = ui->user_name->text();
    QString strPwd = ui->user_pwd->text();
    qDebug() << strName << " " << strPwd;
    if (strName.length() == 0 || strPwd.length() == 0)
    {
        qDebug() << "user name or pwd error";
        return ;
    }
    QString strSql = "select user_id from user_login where user_name = '" + strName + "' and user_pwd = '" + strPwd +"'";
    qDebug() << strSql;
    QSqlQuery query(m_DB);
    if (!query.exec(strSql))
    {
        qDebug() << "sql exec error";
        return;
    }
    if (!query.next())
    {
        qDebug() << "login error";
        return;
    }
    qDebug() << "login ok";
}
完整代码

main.cpp

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//main.cpp
#include "widget.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.InitDatabase();
    w.show();

    return a.exec();
}

widget.h

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//widget.h
#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QSqlDatabase>

namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();

    void InitDatabase();

private slots:
    void on_user_login_clicked();
    void on_user_register_clicked();

private:
    Ui::Widget *ui;
    QSqlDatabase m_DB;
};

#endif // WIDGET_H

widget.cpp

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//widget.cpp
#include <QDebug>
#include <QSqlQuery>
#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::InitDatabase()
{
    qDebug() << "Init database";
    m_DB = QSqlDatabase::addDatabase("QMYSQL");
    m_DB.setHostName("localhost");
    m_DB.setDatabaseName("login_test");
    m_DB.setUserName("root");
    m_DB.setPassword("123456");
    if (!m_DB.open())
    {
         qDebug() << "open error";
         ui->user_login->setEnabled(false);
         ui->user_register->setEnabled(false);
         return;
    }
    qDebug() << "open ok";
}

void Widget::on_user_login_clicked()
{
    QString strName = ui->user_name->text();
    QString strPwd = ui->user_pwd->text();
    qDebug() << strName << " " << strPwd;
    if (strName.length() == 0 || strPwd.length() == 0)
    {
        qDebug() << "user name or pwd error";
        return ;
    }
    QString strSql = "select user_id from user_login where user_name = '" + strName + "' and user_pwd = '" + strPwd +"'";
    qDebug() << strSql;
    QSqlQuery query(m_DB);
    if (!query.exec(strSql))
    {
        qDebug() << "sql exec error";
        return;
    }
    if (!query.next())
    {
        qDebug() << "login error";
        return;
    }
    qDebug() << "login ok";
}

void Widget::on_user_register_clicked()
{
    QString strName = ui->user_name->text();
    QString strPwd = ui->user_pwd->text();
    qDebug() << strName << " " << strPwd;
    if (strName.length() == 0 || strPwd.length() == 0)
    {
        qDebug() << "user name or pwd error";
        return ;
    }
    QString strSql = "insert into user_login (user_name, user_pwd, user_datetime) values ('" + strName
                     + "','" + strPwd + "', now())";
    qDebug() << strSql;
    QSqlQuery query(m_DB);
    if (!query.exec(strSql))
    {
        qDebug() << "sql exec error";
        return;
    }
    qDebug() << "register ok";
}

login_test.pro

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#-------------------------------------------------
#
# Project created by QtCreator 2023-05-06T16:33:01
#
#-------------------------------------------------

QT       += core gui sql

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = login_test
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\
        widget.cpp

HEADERS  += widget.h

FORMS    += widget.ui

出现的问题及修复

运行程序时出现driver not loaded

分析原因

如果Qt只有32位的。连接64位的mysql，需要将libmysql.dll放到qt安装目录lib路径下.

解决方法

将mysql中的libmysql.dll 放在QT的安装目录的 D:\software\Qt\Qt5.8.0\5.8\mingw53_32\lib下即可！

参考链接

Qt5.12.6 连接Mysql8.0 QSqlDatabase:QMySQL driver not loaded

32位Qt连接64位Mysql异常解决方案 异常位：QSqlDatabase:QMySQL driver not loaded