SQLITE ATTACH database

[drescherjm]

Is it possible to attach an SQLITE database and still use the Qt database classes?

[Lykurg]

Well, you could use the sql statement

ATTACH DATABASE filename AS databasename

ATTACH DATABASE filename AS databasename

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then it is pure SQL and has nothing to do with Qt. => You can still use Qt's classes.

Or you can simply use

QSqlDatabase::addDatabase("path/to/file", "mySecondDatabase");
//...
QSqlQuery q(QSqlDatabase::database("mySecondDatabase"));

QSqlDatabase::addDatabase("path/to/file", "mySecondDatabase");
//...
QSqlQuery q(QSqlDatabase::database("mySecondDatabase"));

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[drescherjm]

Well, you could use the sql statement

ATTACH DATABASE filename AS databasename

ATTACH DATABASE filename AS databasename

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then it is pure SQL and has nothing to do with Qt. => You can still use Qt's classes.

Thanks. I was not sure if that method would work.

Or you can simply use

QSqlDatabase::addDatabase("path/to/file", "mySecondDatabase");
//...
QSqlQuery q(QSqlDatabase::database("mySecondDatabase"));

QSqlDatabase::addDatabase("path/to/file", "mySecondDatabase");
//...
QSqlQuery q(QSqlDatabase::database("mySecondDatabase"));

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Now that I expected to work.


Now the question is mainly can I use 2 databases in the same QSqlQuery? I assume with the ATTACH database sql statement I can do this.

[spirit]

Now the question is mainly can I use 2 databases in the same QSqlQuery? I assume with the ATTACH database sql statement I can do this.

with Qt classes you need add two databases using QSqlDatabase::addDatabase, but you need specify different connectionName:

QSqlDatabase db1 = QSqlDatabase::addDatabase("QSQLITE", "db1");
db1.setDatabaseName("path/to/db1");
QSqlDatabase db2 = QSqlDatabase::addDatabase("QSQLITE", "db2");
db2.setDatabaseName("path/to/db2");
//opening databases and etc.

QSqlDatabase db1 = QSqlDatabase::addDatabase("QSQLITE", "db1");
db1.setDatabaseName("path/to/db1");
QSqlDatabase db2 = QSqlDatabase::addDatabase("QSQLITE", "db2");
db2.setDatabaseName("path/to/db2");
//opening databases and etc.

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then you can get data from these databases like this:

...
QSqlDatabase db1 = QSqlDatabase::database("db1");
QSqlDatabase db2 = QSqlDatabase::database("db2");
 
QSqlQuery query1(db1);
//preparing query and execution
...
QSqlQuery query2(db2);
//preparing query and execution
...

...
QSqlDatabase db1 = QSqlDatabase::database("db1");
QSqlDatabase db2 = QSqlDatabase::database("db2");

QSqlQuery query1(db1);
//preparing query and execution
...
QSqlQuery query2(db2);
//preparing query and execution
...

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[spirit]

Or you can simply use

QSqlDatabase::addDatabase("path/to/file", "mySecondDatabase");
//...
QSqlQuery q(QSqlDatabase::database("mySecondDatabase"));

QSqlDatabase::addDatabase("path/to/file", "mySecondDatabase");
//...
QSqlQuery q(QSqlDatabase::database("mySecondDatabase"));

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are you sure that your code will work?
the first parameter of QSqlDatabase::addDatabase should be a name of a driver? i.e. should be:

QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE", "mySecondDatabase");
db.setDatabaseName("path/to/file");
 
//...
QSqlQuery q(QSqlDatabase::database("mySecondDatabase"));

QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE", "mySecondDatabase");
db.setDatabaseName("path/to/file");

//...
QSqlQuery q(QSqlDatabase::database("mySecondDatabase"));

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[Lykurg]

are you sure that your code will work?

Of course not, it was a typo, but since drescherjm figured it out himself...

And I just wonder, why people often ask questions like "Is fooBar working?" without trying it themself before asking. Then they would realize, that it is working.

[spirit]

And I just wonder, why people often ask questions like "Is fooBar working?" without trying it themself before asking. Then they would realize, that it is working.

agree w you.

[tavioman]

Hello all!

Regarding the same subject.

It is possible to attach a database that resides into a QTemporaryFile?

Thank you!

[Lykurg]

It is possible to attach a database that resides into a QTemporaryFile?

Have you tried? Why shouldn't it working? It's a "normal" file. Just use QTemporaryFile::fileName() to work with the file.