database.tables() returned empty after connected to mariadb

lxyevl

After I used driver "QMYSQL" to connect to mariadb, the database.tables() returned

empty. I have tried qt4.8 and qt5.3.2, got the same result.But when I connected to

sqlite, there is no problem.

My OS is opensuse 13.2 64 Bit.

My code is :
#include <QSqlDatabase>
#include <QSqlError>
#include <QDebug>
#include <QStringList>

int main()
{
QSqlDatabase database = QSqlDatabase::addDatabase("QMYSQL");
database.setHostName("localhost");
database.setUserName("lxy");
database.setPassword("qqqqqq");
database.setDatabaseName("information_schema");
if (!database.open())
{
qDebug()<<database.lastError().text();
return 1;
}
qDebug()<<database.tables();
return 0;
}

Program output :
()

SGaist

Hi and welcome to devnet,

Did you rebuild the driver before using it with MariaDB ?

simow

@lxyevl Hi, I can reproduce your behaviour. The culprit seems to be the database itself. For some reason QSqlDatabase::tables() doesn't like to show the tables from the MySQL internal database information_schema. When I use another database, tables() works just fine.
Even when I used QSqlDatabase::tables(QSql::AllTables) -- show everything, including system tables -- the ones contained in information_schema didn't show up. Eventually a bug but might also be a security feature of MySQL not to present internal data?
But I found a workaround. Maybe this would help you:

QSqlQuery q;
q.exec( "select TABLE_NAME,TABLE_SCHEMA from TABLES where TABLE_SCHEMA='information_schema' LIMIT 10" );
while(q.next()) {
 qDebug() << q.value(0) << ", " << q.value(1);
}

This query selects the name and schema from the information_schema.tables system table that contains the meta data of all tables of all databases -- even those in information_schema and itself.

lxyevl

@SGaist No, I didn't. I installed the driver by zypper.

lxyevl

@simow thanks for the answer.