QSqlError("21", "Unable to execute statement", "out of memory")

So instead of this:

QSqlQuery createQuery(DB);
qDebug()<< "open: " << DB.open();

do this

qDebug()<< "open: " << DB.open();
QSqlQuery createQuery(DB);

https://stackoverflow.com/questions/21796961/sqlite-out-of-memory-unable-to-execute-statement