Why can't QSqlDatabase be a dynamic variable?

Seb Tur

I have my connection working via odbc in Linux using

db_static=QSqlDatabase::addDatabase("QODBC","db");

but it fails when I put :

db_ptr=new QSqlDatabase();
db_ptr->addDatabase("QODBC","db");

All other db settings are set by the same methods just changing . to ->

Is it by design that static should be used?

J.Hilk

@Seb-Tur
define it fails

mrjj

Hi

Actually it compiles fine here

auto db_ptr=new QSqlDatabase();
db_ptr->addDatabase("QODBC","db");

Anyway

docs says
"Warning: It is highly recommended that you do not keep a copy of the QSqlDatabase around as a member of a class, as this will prevent the instance from being correctly cleaned up on shutdown. "

So you dont need to store a pointer to it.

it has access to it already via QSqlDatabase::database (static call)

setQuery(SelectStr, QSqlDatabase::database(LOGDBSTR));

so in 99.999% of all cases you do not need to keep a pointer to it :)

SGaist

Hi,

QSqlDatabase is a singleton that manages all the database connections. It's all explained in the documentation of the class.

Beside that, addDatabase is a static method returning a QSqlDatabase instance so what you are doing has in fact no effect and you are manipulating an invalid QSqlDatabase object.