problem creating a mysql database

[TonyB]

Using Qt4.5.2 in Suse 11.1

I am trying to create a mysql database with the following code:

QSqlDatabase maindb = QSqlDatabase::addDatabase("QMYSQL", "main");
maindb.setDatabaseName ("mysql");
maindb.setHostName (url.host());
maindb.setUserName (url.user());
maindb.setPassword (url.pass());
if (!maindb.open()) {
qFatal("opening maindb");
}
QSqlQuery qm(maindb);
QString qs = QString("CREATE DATABASE %1;").arg(dbName);
qm.prepare (qs);
if (!qm.exec()) {
buildError (<snip>);
rc = 1;
}
maindb.close();
QSqlDatabase::removeDatabase (maindb.connectionName());


The exec() call fails with no useful information in the returned QSqlError. The mysql log shows only the following:

090819 14:34:20 8 Connect tonyb@localhost on mysql
8 Init DB mysql
8 Query SET NAMES utf8
8 Quit

i.e. the create database statement never appears.

This code, with the same userid, works okay in Qt3, so it's not a permissions problem. The log there shows

18 Connect tonyb@localhost on mysql
18 Init DB mysql
18 Query CREATE DATABASE KMyMoney
18 Quit

Any ideas? Workarounds?

[caduel]

You should check every statement that could fail (prepare() can fail, too, for example).
Also, try removing the semi-colon ";" at the end of the query.
(I remember that was a problem for me once, I was using Oracle, though.)

HTH

[TonyB]

Many thanks; it was the prepare that was failing with message
Query error No 1295: This command is not supported in the prepared statement protocol yet QMYSQL3: Unable to prepare statement

Now to find a workaround.

[TonyB]

For the record, removing the prepare() and executing the statement directly fixed the problem. Thanks again.

[repaco]

For the record, removing the prepare() and executing the statement directly fixed the problem. Thanks again.

Hi,

I'm using on linux
Mysql 5.0.77-1
QT Creator 1.3.1
QT Libs 4.5.1 (due to Distro compatibility)

This is my code to create DB Schema:

void MainWindow::creadb()
{
    QString db_conti = "conti1";
 
    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("localhost");
    db.setDatabaseName("mysql");
    db.setUserName("root");
    db.setPassword(ui->password->text());
    if (db.open())
    {
        QSqlQuery query;
        query.exec("create database "+db_conti);
 
        qWarning()<<query.lastError();
 
... code for creating tables, views and users...
 
        db.close();
 
    }
 
}

void MainWindow::creadb()
{
    QString db_conti = "conti1";

    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("localhost");
    db.setDatabaseName("mysql");
    db.setUserName("root");
    db.setPassword(ui->password->text());
    if (db.open())
    {
        QSqlQuery query;
        query.exec("create database "+db_conti);

        qWarning()<<query.lastError();

... code for creating tables, views and users...

        db.close();

    }

}

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I'm getting with qWarning() the same your error:

QSqlError(1295, "QMYSQL3: Unable ro prepare statement", "This command is not supported in the prepared statement protocol yet")

But DB Schema is created. Also tables views and users are created without problems.

Do I ignore that error?

Thanks.

[saa7_go]

I'm getting with qWarning() the same your error:

QSqlError(1295, "QMYSQL3: Unable ro prepare statement", "This command is not supported in the prepared statement protocol yet")

But DB Schema is created. Also tables views and users are created without problems.

Do I ignore that error?

Thanks.

Can you post your codes where the warning occurs here?

[repaco]

Hi saa7_go,
sorry delay in answer, I was on holiday.

My complete code is in my previous post.
Row 13

query.exec("create database "+db_conti);

query.exec("create database "+db_conti);

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db_conti contains DB Schema Name

and row 15 to get output log about this command.

DB Schema is created, but query.lastError() gives me error on create database.

thanks in advance

[saa7_go]

Are you sure that this part of your code

void MainWindow::creadb()
{
       .....
        QSqlQuery query;
        query.exec("create database "+db_conti);
 
        qWarning()<<query.lastError();
        .....
}

void MainWindow::creadb()
{
       .....
        QSqlQuery query;
        query.exec("create database "+db_conti);

        qWarning()<<query.lastError();
        .....
}

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prints the warning? Because, you don't do prepare statement like TonyB did.

QSqlQuery qm(maindb);
QString qs = QString("CREATE DATABASE %1").arg(dbName);
qm.prepare (qs);
if (!qm.exec()) {
....
}

QSqlQuery qm(maindb);
QString qs = QString("CREATE DATABASE %1").arg(dbName);
qm.prepare (qs);
if (!qm.exec()) {
....
}

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I've tried your code. No error or warning occurs.

[repaco]

Hi again,
As ToniB wrote, using qm.prepare (qs), no DB Schema is created, with non evidence of error.

ToniB suggested to remove the prepare() and execute the statement directly.

Executing directly, DB Schema is created, but I get error.

It is not a big problem, since DB is created, but I'd like, if it is possible, to fix the problem.

Tks for answer.

[saa7_go]

I think it is a bug . If you want to fix the problem, use Qt 4.6.0 or above.

[repaco]

many thanks.

Ciao.