QSqlQuery and QLineEdit

[GuL]

The result:

DISCO1

Any ideas?

Renan

[spirit]

ok. so, when you call your slot console hasn't any messages, right?

[spirit]

here is small example

#include <QApplication>
#include <QtGui>
#include <QtSql>
 
int main(int argc, char ** argv)
{
    QApplication app(argc, argv);
 
	QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
	db.setDatabaseName("test.db");
 
	if (!db.open()) {
		qDebug() << db.lastError().text();
		return 0;
	}
 
	QSqlQuery query;
	qDebug() << query.exec("CREATE TABLE test (id int PRIMARY KEY, test nvarchar)");
 
	qDebug() << query.exec("INSERT INTO test VALUES(0, 'a')");
	qDebug() << query.exec("INSERT INTO test VALUES(1, 'b')");
	qDebug() << query.exec("INSERT INTO test VALUES(2, 'c')");
	qDebug() << query.exec("INSERT INTO test VALUES(3, 'd')");
	qDebug() << query.exec("SELECT test FROM test WHERE id = 1");
	if (!query.next()) {
		qDebug() << query.lastError().text();
		return 0;
	}
	QLineEdit le(query.value(0).toString());
	le.show();
 
    return app.exec();
}

#include <QApplication>
#include <QtGui>
#include <QtSql>

int main(int argc, char ** argv)
{
    QApplication app(argc, argv);

	QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
	db.setDatabaseName("test.db");
 
	if (!db.open()) {
		qDebug() << db.lastError().text();
		return 0;
	}

	QSqlQuery query;
	qDebug() << query.exec("CREATE TABLE test (id int PRIMARY KEY, test nvarchar)");
	 
	qDebug() << query.exec("INSERT INTO test VALUES(0, 'a')");
	qDebug() << query.exec("INSERT INTO test VALUES(1, 'b')");
	qDebug() << query.exec("INSERT INTO test VALUES(2, 'c')");
	qDebug() << query.exec("INSERT INTO test VALUES(3, 'd')");
	qDebug() << query.exec("SELECT test FROM test WHERE id = 1");
	if (!query.next()) {
		qDebug() << query.lastError().text();
		return 0;
	}
	QLineEdit le(query.value(0).toString());
	le.show();

    return app.exec();
}

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[wysota]

its code didn't compile, than I changed to:

If the code didn't compile, how come you managed to run an non-existing program? "Driver not loaded" is a runtime error, not compiler message.

[GuL]

Copying spirit code to my project didn't compile. here is spirit original code:

void testeMYSQL2::on_pushButton_clicked()
      {
          QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
              db.setHostName("localhost");
              db.setDatabaseName("teste");
              db.setUserName("root");
             db.setPassword("teste1234");
          if (!db.open()) {
                qDebug() << query.lastError().text();
                  return;
          }
           QSqlQuery query;
           if (!query.exec("select nome_prod from produtos where cod_prod = 1")) {
               qDebug() << query.lastError().text();
                return;
           }
             if (!query.next()) {
                qDebug() << query.lastError().text();
                return;
              }
            QString name = query.value(0).toString();
              nameEdit->setText(name);
      }

void testeMYSQL2::on_pushButton_clicked()
      {
          QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
              db.setHostName("localhost");
              db.setDatabaseName("teste");
              db.setUserName("root");
             db.setPassword("teste1234");
          if (!db.open()) {
                qDebug() << query.lastError().text();
                  return;
          }
           QSqlQuery query;
           if (!query.exec("select nome_prod from produtos where cod_prod = 1")) {
               qDebug() << query.lastError().text();
                return;
           }
             if (!query.next()) {
                qDebug() << query.lastError().text();
                return;
              }
            QString name = query.value(0).toString();
              nameEdit->setText(name);
      }

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In line 9, when we test if the database was successfully open,

query.lastError().text();

query.lastError().text();

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I got this error:

.\testemysql2.cpp(50) : error C2065: 'query' : undeclared identifier
.\testemysql2.cpp(50) : error C2228: left of '.lastError' must have class/struct/union
type is ''unknown-type''

when I canged line 9 to:

db.lastError().text();

db.lastError().text();

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I managed to run the program.

About the run-time error: "Driver not loaded"
It happened when I cut line 12 and paste it between line 2 and 3 and line 9 still was query.lastError().text();

I will try your code from the last post, spirit.
I had just install sqlite.

Renan



Renan

[GuL]

it shows me the letter "b" in a QLineEdit. Nice.

I will try to modify my code to work with mysql using your example.

Renan