QSqlRelationalTableModel操作问题

代码如下：
void CRelationDlg::on_proComboBox_currentIndexChanged(const QString &arg1)
{
    if(arg1 == "none")
        return;

    QSqlRelationalTableModel *relationModel = new QSqlRelationalTableModel(this);
    QString tablename = arg1+"_relation";
    QString chanTableName = arg1+"_chan";
    QSqlQuery query;
    QString sql;
    bool newcreate = false;
    if(!db.tables().contains(tablename))
    {
        sql = QString("create table %1(no int primary key,pro varchar,chan varchar,sigID varchar,sigChan int)").arg(tablename);
        query.exec(sql);
        newcreate = true;
        qDebug()<<"create table:"<<tablename;
    }

    relationModel->setEditStrategy(QSqlTableModel::OnFieldChange);
    relationModel->setTable(tablename);

    relationModel->setRelation(2,QSqlRelation(chanTableName,"name","name"));
    relationModel->setRelation(3,QSqlRelation("signalDev","id","id"));
    relationModel->setHeaderData(0, Qt::Horizontal, QObject::tr("序号"));
    relationModel->setHeaderData(1, Qt::Horizontal, QObject::tr("保护类型"));
    relationModel->setHeaderData(2, Qt::Horizontal, QObject::tr("通道名称"));
    relationModel->setHeaderData(3, Qt::Horizontal, QObject::tr("信号源ID"));
    relationModel->setHeaderData(4, Qt::Horizontal, QObject::tr("信号源通道"));

    if((!newcreate))
    {
        relationModel->select();
    }
    ui->tableView->setModel(relationModel);
    ui->tableView->setItemDelegate(new QSqlRelationalDelegate(ui->tableView));

}
有两个问题：1、relationModel->setRelation(2,QSqlRelation(chanTableName,"name","name"));为什么必须两个名字要一样才能正常用呢？按qt助手里的解释，第二个参数应该是chanTableName里的列名，第三个参数应该是目标表的列名，各位看我建的新表里根本就没有name这一列，可是很奇怪，能正常工作，而且把第三个参数改为“chan”就不正常了。
                   2、如果发现数据库里没有这个表，就创建它，这个时候如果调用relationModel->select();运行的就会在下一行ui->tableView->setModel(relationModel);处报错，程序直接死掉，请问这是为什么？ --------------------编程问答-------------------- class CRelationDlg : public QTableView
{
public:
    void on_proComboBox_currentIndexChanged(const QString &arg1)
    {
        if(arg1 == "none")
            return;

        QSqlRelationalTableModel *relationModel = new QSqlRelationalTableModel(this);
        QString tablename = arg1+"_relation";
        QString chanTableName = arg1+"_chan";
        QSqlQuery query;
        QString sql;
        bool newcreate = false;

        if(!QSqlDatabase::drivers().contains("QSQLITE"))
        {
            QMessageBox::information(NULL, "tip", "System can't install SqlLite driver!");
            return;
        }

        QString name = QCoreApplication::applicationDirPath() + "/mytest.db";
        QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE", name);
        db.setDatabaseName(name);
        if (!db.open())
            return;

        query = QSqlQuery(tablename, db);

        tablename = arg1;
        if(!db.tables().contains(tablename))
        {
            sql = QString("create table %1(no int primary key,pro varchar,chan varchar,sigID varchar,sigChan int)").arg(tablename);
            query.exec(sql);
            newcreate = true;
            qDebug()<<"create table:"<<tablename;
        }

        relationModel->setEditStrategy(QSqlTableModel::OnFieldChange);
        relationModel->setTable(tablename);

        //relationModel->setRelation(2,QSqlRelation(chanTableName,"name","name"));
        relationModel->setRelation(3,QSqlRelation("signalDev","id","id"));
        relationModel->setHeaderData(0, Qt::Horizontal, QObject::tr("序号"));
        relationModel->setHeaderData(1, Qt::Horizontal, QObject::tr("保护类型"));
        relationModel->setHeaderData(2, Qt::Horizontal, QObject::tr("通道名称"));
        relationModel->setHeaderData(3, Qt::Horizontal, QObject::tr("信号源ID"));
        relationModel->setHeaderData(4, Qt::Horizontal, QObject::tr("信号源通道"));

        //if((!newcreate))
        {
            relationModel->select();
        }
        setModel(relationModel);
        setItemDelegate(new QSqlRelationalDelegate(this));
    }

};

class CRelationDlg : public QTableView
{
public:
    void on_proComboBox_currentIndexChanged(const QString &arg1)
    {
        if(arg1 == "none")
            return;

        QSqlRelationalTableModel *relationModel = new QSqlRelationalTableModel(this);
        QString tablename = arg1+"_relation";
        QString chanTableName = arg1+"_chan";
        QSqlQuery query;
        QString sql;
        bool newcreate = false;

        if(!QSqlDatabase::drivers().contains("QSQLITE"))
        {
            QMessageBox::information(NULL, "tip", "System can't install SqlLite driver!");
            return;
        }

        QString name = QCoreApplication::applicationDirPath() + "/mytest.db";
        QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE", name);
        db.setDatabaseName(name);
        if (!db.open())
            return;

        query = QSqlQuery(tablename, db);

        tablename = arg1;
        if(!db.tables().contains(tablename))
        {
            sql = QString("create table %1(no int primary key,pro varchar,chan varchar,sigID varchar,sigChan int)").arg(tablename);
            query.exec(sql);
            newcreate = true;
            qDebug()<<"create table:"<<tablename;
        }

        relationModel->setEditStrategy(QSqlTableModel::OnFieldChange);
        relationModel->setTable(tablename);

        //relationModel->setRelation(2,QSqlRelation(chanTableName,"name","name"));
        relationModel->setRelation(3,QSqlRelation("signalDev","id","id"));
        relationModel->setHeaderData(0, Qt::Horizontal, QObject::tr("序号"));
        relationModel->setHeaderData(1, Qt::Horizontal, QObject::tr("保护类型"));
        relationModel->setHeaderData(2, Qt::Horizontal, QObject::tr("通道名称"));
        relationModel->setHeaderData(3, Qt::Horizontal, QObject::tr("信号源ID"));
        relationModel->setHeaderData(4, Qt::Horizontal, QObject::tr("信号源通道"));

        //if((!newcreate))
        {
            relationModel->select();
        }
        setModel(relationModel);
        setItemDelegate(new QSqlRelationalDelegate(this));
    }

};

这是我做的测试，不管怎么调用select都不会死，至于第一个问题，现在不作评论 --------------------编程问答-------------------- 最好不用这个类。用数据库里面的视图。操作简单。

补充：移动开发 ,  Qt