@jsulm You were right. I finally understood what you meant by getting the db at any time. Thank you very much for your help!
This is my working code:
#include "f1_system.h" #include <QtSql/qsqldatabase.h> #include <QtSql/qsqlquery.h> #include <QtSql/qsqlerror.h> #include <QtSql/qsqldriver.h> F1_System::F1_System(QWidget *parent) : QMainWindow(parent) { ui.setupUi(this); QSqlDatabase db = QSqlDatabase::addDatabase("QODBC", "dataB"); QString connectionString = "Driver={SQL Server};Server=DESKTOP-4K9MAS2\\SQLEXPRESS01;Database=Formula1_BD;Trusted_Connection=yes;"; db.setDatabaseName(connectionString); connect(ui.loginPushButton, SIGNAL(clicked()), this, SLOT(validateLogin())); } F1_System::~F1_System() { QSqlDatabase::database("dataB").close(); } void F1_System::validateLogin() { if (QSqlDatabase::database("dataB").open()) { QString selectUser("SELECT Username FROM Users WHERE Username = '" + ui.usernameInputField->text() + "' AND Userpassword = '" + ui.passwordInputField->text() + "';"); QSqlQuery qry(selectUser, QSqlDatabase::database("dataB")); if (qry.next()) ui.label->setText("Status: You are logged in!"); else ui.label->setText("Status: Wrong credentials!\nTry again!"); } else ui.label->setText("Failed to connect to the database!"); }
