数据库

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//例子1#include <QCoreApplication>#include <QTextCodec>#include <QSqlDatabase>#include <QSqlQuery>#include <QTime>#include <QSqlError>#include <QtDebug>#include <QSqlDriver>#include <QSqlRecord>int main(int argc, char *argv[]){    QCoreApplication a(argc, argv);    QTextCodec::setCodecForLocale(QTextCodec::codecForLocale());    QSqlDatabase db =QSqlDatabase::addDatabase("QSQLITE");  //使用QSQLITE驱动    db.setHostName("easybook-3313b0");          //设置数据库主机名    db.setDatabaseName("qtDB.db");              //设置数据库名    db.setUserName("zhouhejun");                //设置数据库用户名    db.setPassword("123456");                   //设置数据库密码    db.open();                                  //打开连接    //创建数据库表    QSqlQuery query;    bool success=query.exec("create table automobil(id int primary key,attribute varchar,type varchar,kind varchar,nation int,carnumber int,elevaltor int,distance int,oil int,temperature int)");    if(success)        qDebug()<<QObject::tr("数据库表创建成功！\n");    else        qDebug()<<QObject::tr("数据库表创建失败！\n");    //查询    query.exec("select * from automobil");    QSqlRecord rec = query.record();  //查询返回的记录    qDebug() << QObject::tr("automobil表字段数：" )<< rec.count();    //插入记录    QTime t;    t.start();    query.prepare("insert into automobil values(?,?,?,?,?,?,?,?,?,?)");    long records=100;    for(int i=0;i<records;i++)    {        //设置对应位置的参数        query.bindValue(0,i);        query.bindValue(1,"四轮");        query.bindValue(2,"轿车");        query.bindValue(3,"富康");        query.bindValue(4,rand()%100);        query.bindValue(5,rand()%10000);        query.bindValue(6,rand()%300);        query.bindValue(7,rand()%200000);        query.bindValue(8,rand()%52);        query.bindValue(9,rand()%100);        //执行插入语句        success=query.exec();          if(!success)        {            QSqlError lastError=query.lastError();            qDebug()<<lastError.driverText()<<QString(QObject::tr("插入失败"));        }    }    qDebug()<<QObject::tr("插入 %1 条记录，耗时：%2 ms").arg(records).arg(t.elapsed());    //排序    t.restart();    success=query.exec("select * from automobil order by id desc");    if(success)        qDebug()<<QObject::tr("排序 %1 条记录，耗时：%2 ms").arg(records).arg(t.elapsed());    else        qDebug()<<QObject::tr("排序失败！");    //更新记录    t.restart();    for(int i=0;i<records;i++)    {       query.clear();       query.prepare(QString("update automobil set attribute=?,type=?,"                             "kind=?,nation=?,"                             "carnumber=?,elevaltor=?,"                             "distance=?,oil=?,"                             "temperature=? where id=%1").arg(i));       query.bindValue(0,"四轮");       query.bindValue(1,"轿车");       query.bindValue(2,"富康");       query.bindValue(3,rand()%100);       query.bindValue(4,rand()%10000);       query.bindValue(5,rand()%300);       query.bindValue(6,rand()%200000);       query.bindValue(7,rand()%52);       query.bindValue(8,rand()%100);       success=query.exec();       if(!success)       {           QSqlError lastError=query.lastError();           qDebug()<<lastError.driverText()<<QString(QObject::tr("更新失败"));       }    }    qDebug()<<QObject::tr("更新 %1 条记录，耗时：%2 ms").arg(records).arg(t.elapsed());    //删除    t.restart();    query.exec("delete from automobil where id=15");    qDebug()<<QObject::tr("删除一条记录，耗时：%1 ms").arg(t.elapsed());    return 0;    //return a.exec();}
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