1、效果演示

1）增删改查效果

2）数据库内容

2、创建数据库及表格2.1 创建数据库

首先在.pro文件添加对sql的支持：QT += core gui sql

领Qt资料→点击「链接」

QString g_connectName = "mySQL_connection";bool MainWindow::createDatabase(){    //检测已连接的方式 - 自定义连接名    if(QSqlDatabase::contains(g_connectName))    {        m_Projdb = QSqlDatabase::database(g_connectName);    }    else    {        m_Projdb = QSqlDatabase::addDatabase("QSQLITE",g_connectName);        //设置数据库路径        QString sDir = QApplication::applicationDirPath();        QString sDataPath = sDir + "/mySql.db";        m_Projdb.setDatabaseName(sDataPath);    }    //打开数据库    if(!m_Projdb.open())    {        QMessageBox::information(this,"提示","数据库创建失败，无法打开!");        return false;    }	// 创建表格    createImageTable();    //关闭数据库    m_Projdb.close();    return true;}

bool MainWindow::createImageTable(){     …………………………         //如果不存在则创建my_table表,id自增,name唯一    const QString cmdSql = R"(                           CREATE TABLE IF NOT EXISTS image_table (                           id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,                           imagename TEXT NOT NULL,                           type CHAR(50) NOT NULL,                           notes TEXT,                           imagedata BLOB NOT NULL                           );)";    //QSqlQuery构造前，需要db已打开并连接;未指定db或者db无效时使用默认连接进行操作    QSqlQuery myQuery(m_Projdb);    if(!myQuery.exec(cmdSql))    {        QString sError = myQuery.lastError().text();        sError = "数据库表格插入数据失败:" + sError;        QMessageBox::information(this,"提示",sError);        m_Projdb.close();        return false;    }     …………………………         return true;}

void MainWindow::on_pushBtn_add_clicked(){    QString strImag = ui->lineEdit_file->text();    QFileInfo fileInfo(strImag);    ………………    QString sName = fileInfo.fileName();    QString sType = fileInfo.suffix();    QString strNote = ui->plainTextEdit_add->toPlainText();    if(ImageFileExist(sName))    {        QMessageBox::information(this,"提示","图片文件已经存在!");        return;    }	//将数据转换为QByteArray类型存储到数据库中    QFile* pFile = new QFile(strImag);    pFile->open(QIODevice::ReadOnly);        QByteArray imageData = pFile->readAll();    pFile->fileName();    pFile->close();    if(!m_Projdb.open())    {        QMessageBox::information(this,"提示","数据库无法打开!");        return;    }    //QSqlQuery构造前，需要db已打开并连接;未指定db或者db无效时使用默认连接进行操作    QSqlQuery myQuery(m_Projdb);    QString cmdSql = "insert into image_table(imagename,type,notes,imagedata) values( '%1','%2','%3',:imagedata)";    cmdSql = QString(cmdSql).arg(sName).arg(sType).arg(strNote);    qDebug() << cmdSql;    myQuery.prepare(cmdSql);    myQuery.bindValue(":imagedata",imageData);    if(!myQuery.exec())    {        QString sError = myQuery.lastError().text();        sError = "数据库表格插入数据失败:" + sError;        QMessageBox::information(this,"提示",sError);        m_Projdb.close();        return;    }    QMessageBox::information(this,"提示","添加成功!");    m_Projdb.close();    // 刷新界面    …………………………}

void MainWindow::on_pushBtn_del_clicked(){    …………………………    //QSqlQuery构造前，需要db已打开并连接;未指定db或者db无效时使用默认连接进行操作    QSqlQuery myQuery(m_Projdb);    QString cmdSql = "DELETE from image_table where imagename = '%1'";    cmdSql = QString(cmdSql).arg(sFileName);    qDebug() << cmdSql;    if(!myQuery.exec(cmdSql))    {        QString sError = myQuery.lastError().text();        sError = "数据库表格删除数据失败:" + sError;        QMessageBox::information(this,"提示",sError);        m_Projdb.close();        return;    }    …………………………    // 刷新界面    ………………………………}

void MainWindow::on_pushBtn_modify_clicked(){    ……………………        QString sNote = dlg.GetNoteString();    QSqlQuery myQuery(m_Projdb);    QString cmdSql = "UPDATE image_table SET notes = '%2' where imagename = '%1'";    cmdSql = QString(cmdSql).arg(sFileName).arg(sNote);    …………………………    // 刷新界面    …………………………}

void MainWindow::on_pushBtn_preview_clicked(){     ………………………………    //QSqlQuery构造前，需要db已打开并连接;未指定db或者db无效时使用默认连接进行操作    QSqlQuery myQuery(m_Projdb);    QString cmdSql = "select * from image_table where imagename = '%1'";    cmdSql = QString(cmdSql).arg(sFileName);    qDebug() << cmdSql;    if(!myQuery.exec(cmdSql))    {        QString sError = myQuery.lastError().text();        sError = "数据库表格查询数据失败:" + sError;        QMessageBox::information(this,"提示",sError);        m_Projdb.close();        return;    }    while (myQuery.next())    {        QString strFileName = myQuery.value(1).toString();        QString strFileType = myQuery.value(2).toString();        QString strNote = myQuery.value(3).toString();        QByteArray bytes = myQuery.value(4).toByteArray();        QBuffer buffer(&bytes);        buffer.open(QIODevice::ReadOnly);        QImageReader reader(&buffer,strFileType.toLatin1());        QImage img = reader.read();        img.save(strFileName);        break;    }    m_Projdb.close();}

bool MainWindow::GetAllImageRecord(){     ………………………………        // 查询表格数据    const QString cmdSql = R"(SELECT * FROM image_table;)";    //QSqlQuery构造前，需要db已打开并连接;未指定db或者db无效时使用默认连接进行操作    QSqlQuery myQuery(m_Projdb);    if(!myQuery.exec(cmdSql))    {        QString sError = myQuery.lastError().text();        sError = "数据库表格插入数据失败:" + sError;        QMessageBox::information(this,"提示",sError);        m_Projdb.close();        return false;    }    while (myQuery.next())    {        QString sFileName, sFileType,sNotes;        for (int i = 0; i < myQuery.record().count(); i++)        {            QString strFieldName = myQuery.record().fieldName(i);            QVariant value = myQuery.record().value(i);            if(strFieldName == "imagename")            {                QString strValue = value.toString();                sFileName = strValue;            }            if(strFieldName == "type")            {                QString strValue = value.toString();                sFileType = strValue;            }            if(strFieldName == "notes")            {                QString strValue = value.toString();                sNotes = strValue;            }        }		if (!sFileName.isEmpty() && !sFileType.isEmpty())		{			FileInfo fileInfo;			fileInfo.sName = sFileName;			fileInfo.sType = sFileType;            fileInfo.sNotes = sNotes;			m_vecImageFile.push_back(fileInfo);		}    }   …………………………   }