无法从 qt 中的 SQLITE 检索数据

编程问答 2022-05-02

问题描述

代码

    void retrive::on_pushButton_clicked()
{
    QString id=ui->label_id->text();

    MainWindow  log;
    bool ok=log.openconnection();
    if(!ok)QMessageBox::critical(this,"error","Failed to open database");

    QsqlQuery qry;
    qry.prepare("select * from Students where ID='"+id+"'");
    if(qry.exec()){
            ui->NAME_label->setText(qry.value(1).toString());
            ui->CC_label->setText(qry.value(2).toString());
            ui->CGPA_label->setText(qry.value(3).toString());
            ui->MOBILE_label->setText(qry.value(4).toString());
            ui->ADDRESS_label->setText(qry.value(5).toString());
    }else
        QMessageBox::critical(this,qry.lastError().text());

    log.closeconnection();
}

我试图从 qt 中的 sqlite 数据库中检索数据，但它显示以下错误。 我现在该怎么办？

QsqlDatabasePrivate::removeDatabase: connection 'qt_sql_default_connection' is still in use,all queries will cease to work.
QsqlDatabasePrivate::addDatabase: duplicate connection name 'qt_sql_default_connection',old connection removed.
QsqlQuery::value: not positioned on a valid record
QsqlQuery::value: not positioned on a valid record
QsqlQuery::value: not positioned on a valid record
QsqlQuery::value: not positioned on a valid record
QsqlQuery::value: not positioned on a valid record
QsqlDatabasePrivate::removeDatabase: connection 'qt_sql_default_connection' is still in use,all queries will cease to work.

我现在能做什么？

解决方法

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c++databasedatabasedatabaseqtqtqtqtsqlsqlite