MySQL doesn't return data
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Hi i'm having problems with reading data out of database.
The connection should be fine as bool ok = m_db.open() returns 1.
i connect to database like this:
m_db = QSqlDatabase::addDatabase("QMYSQL"); m_db.setHostName(m_hostname); m_db.setUserName(m_username); m_db.setPort(m_port); m_db.setPassword(m_password); bool ok = m_db.open();Then i select dbname with other function:
void SqlDB::SelectDB(QString &dbname){ std::cout <<"SelectDB" << " " << dbname.toStdString() << std::endl; m_db.setDatabaseName(dbname); }And then i try to use other function to get the data.
std::cout <<"GetTables" << std::endl; QSqlDriver *driver = m_db.driver(); std::cout << "isopen:" << m_db.isOpen(); std::cout << "db name=" <<m_db.databaseName().toStdString(); QSqlRecord record = driver->record("auto"); QSqlQuery q; q.exec("SELECT * from auto"); while(q.next()){ QString val; val = q.value(0).toString(); std::cout << val.toStdString(); } std::cout << "record count = " << record.count();isopen = 1,
dbname is correct, but it still gives me record.count() = 0.I have also tried to use db.tables(), but it returns 0 lines too.
Thanks,
Izba@Izba What does http://doc.qt.io/qt-5/qsqlquery.html#lastError return?
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@Izba What does http://doc.qt.io/qt-5/qsqlquery.html#lastError return?
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QSqlError err = m_db.lastError(); std::cout << err.databaseText().toStdString(); std::cout << err.text().toStdString(); std::cout << err.driverText().toStdString();I cant get it to return anything. Maybe i'm trying to debug it wrong?
@Izba I mean the error from QSqlQuery
QSqlQuery q; q.exec("SELECT * from auto"); while(q.next()){ QString val; val = q.value(0).toString(); std::cout << val.toStdString(); } std::cout << "record count = " << record.count(); qDebug() << q.lastError(); -
@Izba I mean the error from QSqlQuery
QSqlQuery q; q.exec("SELECT * from auto"); while(q.next()){ QString val; val = q.value(0).toString(); std::cout << val.toStdString(); } std::cout << "record count = " << record.count(); qDebug() << q.lastError();@jsulm said in MySQL doesn't return data:
val = q.value(0).toString(); std::cout << val.toStdString();}
std::cout << "record count = " << record.count();
qDebug() << q.lastError();Oh yeah it gives me an error that no database selected, but m_db.databaseName still gives me correct database.
I have set the database by m_db.setDatabaseName().
Do i need to set it some other way that the query would recognize it?
Thanks
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@jsulm said in MySQL doesn't return data:
val = q.value(0).toString(); std::cout << val.toStdString();}
std::cout << "record count = " << record.count();
qDebug() << q.lastError();Oh yeah it gives me an error that no database selected, but m_db.databaseName still gives me correct database.
I have set the database by m_db.setDatabaseName().
Do i need to set it some other way that the query would recognize it?
Thanks
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QSqlQuery q(QSqlDatabase::database("mottonen")); q.exec("SELECT * from auto"); while(q.next()){ QString val; val = q.value(0).toString(); std::cout << val.toStdString(); } qDebug() << q.lastError();Still same error:
QSqlError("1046", "QMYSQL: Kyselyn suorittaminen epäonnistui", "No database selected") -
QSqlQuery q(QSqlDatabase::database("mottonen")); q.exec("SELECT * from auto"); while(q.next()){ QString val; val = q.value(0).toString(); std::cout << val.toStdString(); } qDebug() << q.lastError();Still same error:
QSqlError("1046", "QMYSQL: Kyselyn suorittaminen epäonnistui", "No database selected") -
@Izba Please read documentation:
"Sets the connection's database name to name. To have effect, the database name must be set before the connection is opened."
http://doc.qt.io/qt-5/qsqldatabase.html#setDatabaseName -
@Izba Please read documentation:
"Sets the connection's database name to name. To have effect, the database name must be set before the connection is opened."
http://doc.qt.io/qt-5/qsqldatabase.html#setDatabaseName
