Connectingto MySQL with QODBC3

**Philip_Anselmo** · 6th June 2006, 22:39

Hi I'm trying to connect to a MySQL 3.23 on a Fedora Core 1 with an app I made on Qt 3.1.2
I installed the QODBC3 plugin through yum

yum install qt-ODBC

it installed also the Unix-ODBC driver

so I connect to MySQL server as this:

Qt Code:

Switch view

QSqlDatabase *defaultDB;
bool creaConexion()
{
 
    defaultDB = QSqlDatabase::addDatabase( DBDRIVER );
    defaultDB->setHostName( DB_HOSTNAME );
    defaultDB->setDatabaseName( "DRIVER={MySQL};Server="+DB_HOSTNAME+";Database="+DB_NOM+";Uid= "+DB_USR+";Pwd="+DB_PASS+";" );
    defaultDB->setUserName( DB_USR );
    defaultDB->setPassword( DB_PASS );
 
    if ( ! defaultDB->open() ) {
	QMessageBox::warning(0, "Fallo de conexiÃ³n", "No se pudo conectar con la base de datos: " + DB_NOM  + "tabla: " + DB_TABLA + "\n" +  defaultDB->lastError().driverText());
        return FALSE;
    }
    QMessageBox::information(0,"ConexiÃ³n estabecida","Conectado a: " + DB_HOSTNAME + " " + "tabla: " + DB_TABLA + " "+ DB_NOM);
    return TRUE;
}

QSqlDatabase *defaultDB;
bool creaConexion()
{

    defaultDB = QSqlDatabase::addDatabase( DBDRIVER );
    defaultDB->setHostName( DB_HOSTNAME );
    defaultDB->setDatabaseName( "DRIVER={MySQL};Server="+DB_HOSTNAME+";Database="+DB_NOM+";Uid= "+DB_USR+";Pwd="+DB_PASS+";" );
    defaultDB->setUserName( DB_USR );
    defaultDB->setPassword( DB_PASS );
    
    if ( ! defaultDB->open() ) {
	QMessageBox::warning(0, "Fallo de conexiÃ³n", "No se pudo conectar con la base de datos: " + DB_NOM  + "tabla: " + DB_TABLA + "\n" +  defaultDB->lastError().driverText());
        return FALSE;
    }
    QMessageBox::information(0,"ConexiÃ³n estabecida","Conectado a: " + DB_HOSTNAME + " " + "tabla: " + DB_TABLA + " "+ DB_NOM);
    return TRUE;
}

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I don't see what's wrong so I ask you for help

I'm geting this error:

Warning: QSqlDatabaseManager unable to open database: [unixODBC][Driver Manager]Data source name not found, and no default driver specified : QODBC3: Unable to connect

**wysota** · 6th June 2006, 23:29

You have to setup the database in Unix-ODBC. Unfortunately I know nothing about it

Maybe mr Google does.

**Philip_Anselmo** · 7th June 2006, 16:50

I checked the driver configuration in odbc

the /etc/odbcnist.ini looks like this:

Qt Code:

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# Example driver definitinions
#
#
 
# Included in the unixODBC package
[PostgreSQL]
Description     = ODBC for PostgreSQL
Driver          = /usr/lib/libodbcpsql.so
Setup           = /usr/lib/libodbcpsqlS.so
FileUsage       = 1
 
 
# Driver from the MyODBC package
# Setup from the unixODBC package
[MySQL]
Description     = ODBC for MySQL
Driver          = /usr/lib/libmyodbc.so
Setup           = /usr/lib/libodbcmyS.so
FileUsage       = 1

# Example driver definitinions
#
#

# Included in the unixODBC package
[PostgreSQL]
Description     = ODBC for PostgreSQL
Driver          = /usr/lib/libodbcpsql.so
Setup           = /usr/lib/libodbcpsqlS.so
FileUsage       = 1


# Driver from the MyODBC package
# Setup from the unixODBC package
[MySQL]
Description     = ODBC for MySQL
Driver          = /usr/lib/libmyodbc.so
Setup           = /usr/lib/libodbcmyS.so
FileUsage       = 1

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the only problem is that I can't find /usr/lib/libmyodbc.so
that file is missing on this fedora core 1 wich uses unixODBC 2.2.8 and I can't install other version because of the dependencies and I just can't find the 2.2.8 version on the net

I just can't work like that

How can I get that damn .so file?

**Philip_Anselmo** · 7th June 2006, 17:00

jjaja nevermind I just founded the myodbc on the fedora website :P

but now it throwsme a segment violation :S:S:S

is this code right?:

Qt Code:

Switch view

QSqlDatabase *defaultDB;
bool creaConexion()
{
 
    defaultDB = QSqlDatabase::addDatabase( DBDRIVER );
    defaultDB->setHostName( DB_HOSTNAME );
    defaultDB->setDatabaseName( "DRIVER={MySQL};Server="+DB_HOSTNAME+";Database="+DB_NOM+";Uid= "+DB_USR+";Pwd="+DB_PASS+";" );
    defaultDB->setUserName( DB_USR );
    defaultDB->setPassword( DB_PASS );
 
    if ( ! defaultDB->open() ) {
	QMessageBox::warning(0, "Fallo de conexiÃ³n", "No se pudo conectar con la base de datos: " + DB_NOM  + "tabla: " + DB_TABLA + "\n" +  defaultDB->lastError().driverText());
        return FALSE;
    }
    QMessageBox::information(0,"ConexiÃ³n estabecida","Conectado a: " + DB_HOSTNAME + " " + "tabla: " + DB_TABLA + " "+ DB_NOM);
    return TRUE;
}

QSqlDatabase *defaultDB;
bool creaConexion()
{

    defaultDB = QSqlDatabase::addDatabase( DBDRIVER );
    defaultDB->setHostName( DB_HOSTNAME );
    defaultDB->setDatabaseName( "DRIVER={MySQL};Server="+DB_HOSTNAME+";Database="+DB_NOM+";Uid= "+DB_USR+";Pwd="+DB_PASS+";" );
    defaultDB->setUserName( DB_USR );
    defaultDB->setPassword( DB_PASS );
    
    if ( ! defaultDB->open() ) {
	QMessageBox::warning(0, "Fallo de conexiÃ³n", "No se pudo conectar con la base de datos: " + DB_NOM  + "tabla: " + DB_TABLA + "\n" +  defaultDB->lastError().driverText());
        return FALSE;
    }
    QMessageBox::information(0,"ConexiÃ³n estabecida","Conectado a: " + DB_HOSTNAME + " " + "tabla: " + DB_TABLA + " "+ DB_NOM);
    return TRUE;
}

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**wysota** · 7th June 2006, 17:39

Check if defaultDB!=0 before dereferencing the pointer (line 6).

**Philip_Anselmo** · 7th June 2006, 18:01

Qt Code:

Switch view

QSqlDatabase *defaultDB;
bool creaConexion()
{
 
    defaultDB = QSqlDatabase::addDatabase( DBDRIVER );
    if (defaultDB!=0)
    {
	defaultDB->setHostName( DB_HOSTNAME );
 	qWarning("host seteado");
	defaultDB->setDatabaseName( "DRIVER={MySQL};Server="+DB_HOSTNAME+";Database="+DB_NOM+";Uid= "+DB_USR+";Pwd="+DB_PASS+";" );
	defaultDB->setUserName( DB_USR );
	defaultDB->setPassword( DB_PASS );
 
	if ( ! defaultDB->open() )
	{
	    QMessageBox::warning(0, "Fallo de conexiÃ³n", "No se pudo conectar con la base de datos: " + DB_NOM  + "tabla: " + DB_TABLA + "\n" +  defaultDB->lastError().driverText());
	    return FALSE;
	}
	QMessageBox::information(0,"ConexiÃ³n estabecida","Conectado a: " + DB_HOSTNAME + " " + "tabla: " + DB_TABLA + " "+ DB_NOM);
	qWarning("No pesko");
	return FALSE;
    }
}

QSqlDatabase *defaultDB;
bool creaConexion()
{

    defaultDB = QSqlDatabase::addDatabase( DBDRIVER );
    if (defaultDB!=0)
    {
	defaultDB->setHostName( DB_HOSTNAME );
 	qWarning("host seteado");
	defaultDB->setDatabaseName( "DRIVER={MySQL};Server="+DB_HOSTNAME+";Database="+DB_NOM+";Uid= "+DB_USR+";Pwd="+DB_PASS+";" );
	defaultDB->setUserName( DB_USR );
	defaultDB->setPassword( DB_PASS );
	
	if ( ! defaultDB->open() )
	{
	    QMessageBox::warning(0, "Fallo de conexiÃ³n", "No se pudo conectar con la base de datos: " + DB_NOM  + "tabla: " + DB_TABLA + "\n" +  defaultDB->lastError().driverText());
	    return FALSE;
	}
	QMessageBox::information(0,"ConexiÃ³n estabecida","Conectado a: " + DB_HOSTNAME + " " + "tabla: " + DB_TABLA + " "+ DB_NOM);
	qWarning("No pesko");
	return FALSE;
    }
}

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It stills says segment violation

If I comment the last part.. from if ( ! defaultDB->open() ) 'till the last return
It doesn't tells me the segment violation stuff.. but when I try to fill the qdatatable with a qsqlcursor the segment violation stuff comes out

so I have to find a way to do that :S any ideas?
because I don't have any

**wysota** · 7th June 2006, 18:11

Try with some other driver (like QSQLITE or better yet with QMYSQL) to see if your code is alright. If it won't crash, then it means there is something wrong with the driver.

**Philip_Anselmo** · 7th June 2006, 20:28

I've tryed with QMySQL3 and it works perfectly, but i'm not able to use the qmysql on windows so I can't use it now because I need to work with the same code on Linux Qt 3.1.2 and windows Qt 4.1.2-3

My question is.. once I made the connection with odbc, the workaround with qsqlcursor is the same as with qmysql3?

**wysota** · 7th June 2006, 21:13

Originally Posted by Philip_Anselmo

I've tryed with QMySQL3 and it works perfectly, but i'm not able to use the qmysql on windows

Why not?

so I can't use it now because I need to work with the same code on Linux Qt 3.1.2 and windows Qt 4.1.2-3

You won't be, because Qt3 and Qt4 database interfaces differ (for example addDatabase of one of them returns a pointer and in the other -- an object).

My question is.. once I made the connection with odbc, the workaround with qsqlcursor is the same as with qmysql3?

The general idea of using Qt database abstraction is that it is abstract -- it doesn't depend on the driver used. You should be able to use ODBC and MYSQL drivers using the same code. The only line which differs will be the one which chooses the driver type, but you can work it around using #ifdef-#endif constructions.

**Philip_Anselmo** · 7th June 2006, 22:08

I know the diference on qt3 and 4 with the pointer on the database connection

the problem on using qmysql on windows... well at this time I just think it's imposible... at least everything I've tryed didn't work I just give up on that.. if you search all my posts here I think you'll find out that 4/5 of them are about the qmysql pluginI even made a how-to about it and it worked for others but not here on 3 windows!!! Qt hates me

I just hope ODBC works... if not.. well.. no more qt+mysql for me

by the way I think it isn't connecting:

Qt Code:

Switch view

QSqlDatabase *defaultDB;
bool creaConexion()
{
    defaultDB = QSqlDatabase::addDatabase( DBDRIVER );
    if (defaultDB!=0)
    {
	defaultDB->setHostName( DB_HOSTNAME );
 	qWarning("host seteado");
	defaultDB->setDatabaseName( "Driver={MySQL};Server="+DB_HOSTNAME+";Database="+DB_NOM+";Uid="+DB_USR+";Pwd="+DB_PASS+";" );
	defaultDB->setUserName( DB_USR );
	defaultDB->setPassword( DB_PASS );
 
	if ( ! defaultDB->open() )
	{
	    QMessageBox::warning(0, "Fallo de conexiÃ³n", "No se pudo conectar con la base de datos: " + DB_NOM  + "tabla: " + DB_TABLA + "\n" +  defaultDB->lastError().driverText());
	    return FALSE;
	}
	QMessageBox::information(0,"ConexiÃ³n estabecida","Conectado a: " + DB_HOSTNAME + " " + "tabla: " + DB_TABLA + " "+ DB_NOM);
	qWarning("No pesko");
	return TRUE;
    }
}

QSqlDatabase *defaultDB;
bool creaConexion()
{
    defaultDB = QSqlDatabase::addDatabase( DBDRIVER );
    if (defaultDB!=0)
    {
	defaultDB->setHostName( DB_HOSTNAME );
 	qWarning("host seteado");
	defaultDB->setDatabaseName( "Driver={MySQL};Server="+DB_HOSTNAME+";Database="+DB_NOM+";Uid="+DB_USR+";Pwd="+DB_PASS+";" );
	defaultDB->setUserName( DB_USR );
	defaultDB->setPassword( DB_PASS );
	
	if ( ! defaultDB->open() )
	{
	    QMessageBox::warning(0, "Fallo de conexiÃ³n", "No se pudo conectar con la base de datos: " + DB_NOM  + "tabla: " + DB_TABLA + "\n" +  defaultDB->lastError().driverText());
	    return FALSE;
	}
	QMessageBox::information(0,"ConexiÃ³n estabecida","Conectado a: " + DB_HOSTNAME + " " + "tabla: " + DB_TABLA + " "+ DB_NOM);
	qWarning("No pesko");
	return TRUE;
    }
}

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the qWarning tells me:

QODBC3: Unable to connect

and on console:

QODBCDriver::disconnect: Unable to disconnect datasource Error: [unixODBC][Driver Manager]Connnection does not exist

**wysota** · 8th June 2006, 00:14

Originally Posted by Philip_Anselmo

the problem on using qmysql on windows... well at this time I just think it's imposible... at least everything I've tryed didn't work I just give up on that.. if you search all my posts here I think you'll find out that 4/5 of them are about the qmysql pluginI even made a how-to about it and it worked for others but not here on 3 windows!!! Qt hates me

You're probably making the same mistake all the time. But doesn't Qt for Windows come with a precompiled binary mysql driver? Or maybe you could ask someone else to compile the driver for you? There is really no reason to reinvent the wheel...

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