QT Sqlite 内存模式 简单读写

//本文描述了QT Sqlite 内存模式 ，使用QT 自带库文件，写入和读取。

//QT 6.2.4 MSVC2019调试通过。

//需要在pro文件中加入QT += sql

#include <QCoreApplication>
#include <QSqlDatabase>
#include <QSqlQuery>
#include <QDebug>
#include <QSqlDriver>
//#include <QSqlError>
//#include <QStringList>
//#include <QVariant>

static bool createConnection()
{

//addDatabase的原型是

//QSqlDatabase::addDatabase

//                            (const QString &type,/*类型*/

//                        const QString &connectionName = QLatin1String(defaultConnection))//连接名称
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName(":memory:");
    if(!db.open())
    {
        qDebug()<<"sqlite memory db is not open";
        return false;
    }
    QSqlQuery query;
    query.exec("create table student(id int primary key,name vachar(20))");//
    query.exec("insert into student values(0,'Jack_Ma')");
    query.exec("insert into student values(1,'HuaTeng_Ma')");
    query.exec("insert into student values(2,'QiangDong_Liu')");
    query.exec("insert into student values(3,'YanHong_Li')");
    query.exec("insert into student values(4,'Lei_Ding')");
    return true;
}

int main(int argc,char* argv[])
{
    QCoreApplication a(argc, argv);
    qDebug()<<"Available drivers:";
    QStringList dataDrivers = QSqlDatabase::drivers();
    for(auto item:dataDrivers)
    {
        qDebug()<<item;
    }
    if(!createConnection())
        return 1;
    QSqlQuery query;

    query.exec("select * from student");
    qDebug()<<"all records:";
    while(query.next())
    {
        qDebug()<<query.value(0).toInt()<<query.value(1).toString();//逐行打印各记录
    }
    query.exec("select count (*) from student");
    qDebug()<<"records count number:";
    while(query.next())
    {
        qDebug()<<query.value(0).toInt();//打印记录数
    }
    return a.exec();
}