Re: [SailfishDevel] Connect to 2 databases

[Chris Walker]

On Wed, 14 Sep 2016 23:40:50 +0200
Matthias Fehring  wrote:

> Am Donnerstag, 8. September 2016, 14:40:16 CEST schrieb Chris Walker:
> > Can anybody point me in the direction of some C++ code to connect to
> > two SQL databases please?  
> 
> Does it have to be pure C++ code? If not and if it can be the Qt way,
> read on. :)
> 
> > I want to have one set as read-only and the other as read-write.
> > 
> > Whatever I'm doing is wrong as I always end up with a default
> > connection.  
> 
> Have a look at QSqlDatabase and it's addDatabase() method. [1]

Thank you Matthias for the examples. I'll take a look.
___
SailfishOS.org Devel mailing list
To unsubscribe, please send a mail to devel-unsubscr...@lists.sailfishos.org

Re: [SailfishDevel] Connect to 2 databases

[Chris Walker]

On Wed, 14 Sep 2016 23:34:18 +0300
"E.S. Rosenberg"  wrote:

> Assuming you need SQLite since you are developing for SailfishOS the
> first result here seems to be what you are looking for:
> https://www.google.nl/search?q=c%2B%2B+sqlite
> 
> Instead of creating one SQLite object you create 2 or more, one for
> each database though if you are opening a lot of databases you
> might want to consider if they shouldn't all be different tables in
> the same database.

I can't add the tables to the first database as I want to use that 'as
is' and hence read only.

> Of course you could also be more forthcoming about what exact db
> you're trying to connect to and what you tried so that we don't do
> double work for you, I believe as a community we need to be helpful
> etc. but as a member looking for help I also need to do my due
> diligence, without that expect short basic answers or none...

As a beer drinker, I am a member of CAMRA - http://www.camra.org.uk/

They have an app for iOS and Android and while I do have the Android
app on my phone I think it's awful. So I'm trying to write an app to
use the CAMRA database which happens to be a sqlite file. CAMRA update
the app and data annually and I want to be able to simply overwrite the
existing database with the new one each year but retain my own database
for noting things like which beers I've drunk.

I've checked with the company that wrote the app for CAMRA and they say
that they try to maintain the same database structure and numbering
each year but it falls to CAMRA to maintain the numbering as they
supply the data to the app company. I'm assuming (perhaps naively) that
it will remain constant.

I might also have another app for noting which pubs I've visited as
CAMRA list pub data in the same sqlite database.

> The general idea should be along these lines:
> 
> sqlite3 *db1, *db2;
> sqlite_open(path1, );
> sqlite_open(path2, );
> 
> Regards,
> Eli

Thanks very much. That gives me something to work with.

I apologise if my first reply was a bit terse. That wasn't my intention.
___
SailfishOS.org Devel mailing list
To unsubscribe, please send a mail to devel-unsubscr...@lists.sailfishos.org

Re: [SailfishDevel] Connect to 2 databases

[Matthias Fehring]

Am Donnerstag, 8. September 2016, 14:40:16 CEST schrieb Chris Walker:
> Can anybody point me in the direction of some C++ code to connect to
> two SQL databases please?

Does it have to be pure C++ code? If not and if it can be the Qt way, read on. 
:)

> I want to have one set as read-only and the other as read-write.
> 
> Whatever I'm doing is wrong as I always end up with a default
> connection.

Have a look at QSqlDatabase and it's addDatabase() method. [1]

Example for two SQLite databases:

You have to set a connection name for each database.

> QSqlDatabase rodb = QSqlDatabase::addDatabase(QStringLiteral("QSQLITE"), 
QStringLiteral("rodb"));
> rodb.setConnectOptions(QStringLiteral("QSQLITE_OPEN_READONLY");
> rodb.setDatabaseName(QStringLiteral("/full/path/to/ro_database.sqlite"));
>
> if (rodb.open()) {
>   QSqlQuery qro(rodb);
>   .
> }
>
> QSqlDatabase rwdb = QSqlDatabase::addDatabase(QStringLiteral("QSQLITE"), 
QStringLiteral("rwdb"));
> rwdb.setDatabaseName(QStringLiteral("/full/path/to/rw_database.sqlite"));
> if (rwdb.open()) {
>   QSqlQuery qrw(rwdb);
>   .
> }

Later on you can refer everywhere in your application to the databases by 
using the connection names (rodb and rwdb):

> QSqlDatabase rodb = QSqlDatabase::database(QStringLiteral("rodb"));
> QSqlQuery q(rodb);
> 


Best greetings
Matthias


[1] http://doc.qt.io/qt-5/qsqldatabase.html#addDatabase

-- 
Das Gesetz hat zum Schneckengang verdorben, was Adlerflug geworden wäre.
(Friedrich Schiller - Die Räuber)

Und der Buschfunk spielt gerade "Pikse Palve" von "In Extremo".

www.buschmann23.de
GPG-Key: 3A70A936614C3258
GPG Fingerprint: D786 DDF8 4CA9 00BC CDE0 9A5F CCC5 125D 6E87 D4FC

signature.asc
Description: This is a digitally signed message part.
___
SailfishOS.org Devel mailing list
To unsubscribe, please send a mail to devel-unsubscr...@lists.sailfishos.org

Re: [SailfishDevel] Connect to 2 databases

[E.S. Rosenberg]

Assuming you need SQLite since you are developing for SailfishOS the first
result here seems to be what you are looking for:
https://www.google.nl/search?q=c%2B%2B+sqlite

Instead of creating one SQLite object you create 2 or more, one for each
database though if you are opening a lot of databases you might want to
consider if they shouldn't all be different tables in the same database.

Of course you could also be more forthcoming about what exact db you're
trying to connect to and what you tried so that we don't do double work for
you, I believe as a community we need to be helpful etc. but as a member
looking for help I also need to do my due diligence, without that expect
short basic answers or none...

The general idea should be along these lines:

sqlite3 *db1, *db2;
sqlite_open(path1, );
sqlite_open(path2, );

Regards,
Eli

2016-09-14 18:03 GMT+03:00 Chris Walker <
cdw_noki...@the-walker-household.co.uk>:

> On Wed, 14 Sep 2016 00:19:02 +0300
> "E.S. Rosenberg"  wrote:
>
> > 2 different connection objects?
> >
> > 2016-09-08 16:40 GMT+03:00 Chris Walker <
> > cdw_noki...@the-walker-household.co.uk>:
> >
> > > Can anybody point me in the direction of some C++ code to connect to
> > > two SQL databases please?
>
> I'd like to point out the wording of my question? I said ".. point me in
> the direction of some code". So can anybody help with that please?
> ___
> SailfishOS.org Devel mailing list
> To unsubscribe, please send a mail to devel-unsubscribe@lists.
> sailfishos.org
>
___
SailfishOS.org Devel mailing list
To unsubscribe, please send a mail to devel-unsubscr...@lists.sailfishos.org

Re: [SailfishDevel] Connect to 2 databases

[Chris Walker]

On Wed, 14 Sep 2016 00:19:02 +0300
"E.S. Rosenberg"  wrote:

> 2 different connection objects?
> 
> 2016-09-08 16:40 GMT+03:00 Chris Walker <
> cdw_noki...@the-walker-household.co.uk>:
> 
> > Can anybody point me in the direction of some C++ code to connect to
> > two SQL databases please?

I'd like to point out the wording of my question? I said ".. point me in
the direction of some code". So can anybody help with that please?
___
SailfishOS.org Devel mailing list
To unsubscribe, please send a mail to devel-unsubscr...@lists.sailfishos.org

Re: [SailfishDevel] Connect to 2 databases

[E.S. Rosenberg]

2 different connection objects?

2016-09-08 16:40 GMT+03:00 Chris Walker <
cdw_noki...@the-walker-household.co.uk>:

> Can anybody point me in the direction of some C++ code to connect to
> two SQL databases please?
>
> I want to have one set as read-only and the other as read-write.
>
> Whatever I'm doing is wrong as I always end up with a default
> connection.
> ___
> SailfishOS.org Devel mailing list
> To unsubscribe, please send a mail to devel-unsubscribe@lists.
> sailfishos.org
>
___
SailfishOS.org Devel mailing list
To unsubscribe, please send a mail to devel-unsubscr...@lists.sailfishos.org

[SailfishDevel] Connect to 2 databases

[Chris Walker]

Can anybody point me in the direction of some C++ code to connect to
two SQL databases please?

I want to have one set as read-only and the other as read-write.

Whatever I'm doing is wrong as I always end up with a default
connection.
___
SailfishOS.org Devel mailing list
To unsubscribe, please send a mail to devel-unsubscr...@lists.sailfishos.org