I was not able to reproduce the problem
Code:
#include <QtCore>
#include <QtSql>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName("customdb");
if (!db.open())
qDebug() << db.lastError();
QSqlQuery q;
q.prepare("create table FilterNumTable "
"(id integer,"
"FNumber varchar(20),"
"Enable varchar(30),"
"Disable varchar(30),"
"PRIMARY KEY (FNumber , id))");
if (!q.exec())
qDebug() << q.lastError();
qDebug() << db.tables();
db.close();
}