SQLite, QString and QByteArray

p-himik

Here is some code:
@QSqlDatabase db = QSqlDatabase::addDatabase( "QSQLITE" );
db.setDatabaseName( ":memory:" );
db.open();
QSqlQuery query( db );
query.exec( "create table q(a,b)" );
query.prepare( "insert into q values(?,?)" );
query.addBindValue( QString( "123" ) );
query.addBindValue( QByteArray( "234" ) );
query.exec();

query.exec( "select * from q" );
qDebug() << query.next();

query.prepare( "select * from q where a=?" );
query.addBindValue( QString( "123" ) );
query.exec();
qDebug() << query.next();
query.prepare( "select * from q where a=?" );
query.addBindValue( QByteArray( "123" ) );
query.exec();
qDebug() << query.next();
query.prepare( "select * from q where b=?" );
query.addBindValue( QString( "234" ) );
query.exec();
qDebug() << query.next();
query.prepare( "select * from q where b=?" );
query.addBindValue( QByteArray( "234" ) );
query.exec();
qDebug() << query.next();@

And here is output:
@true
true
false
false
true @

I've just wrote this and realized - are QByteArray values stored as BLOB?

fluca1978

I'm not sure, but you haven't specified any type for the columns into your table:

@query.exec( "create table q(a,b)" );@

so it could be a default cast?

p-himik

Specifying type for SQLite is just a recommendation for driver (or at least i remember it so). It determines type automatically. And as i understand somehow SQLite driver thinks that QByteArray( "234" ) is BLOB.

lgeyer

Well, QByteArray actually is a BLOB ("The QByteArray class provides an array of bytes."), so why should it be stored as anything else then a BLOB?

p-himik

Yes, i understand it. I think i misunderstood the way values are passed to SQLite backend.
The only question (not related to Qt though) now is why
@SELECT * FROM q WHERE a='123';@
gives nothing while
@SELECT * FROM q WHERE a like '123';@
outputs the right row? It's been a little confusing when i tried to get values from table with the first query and got empty query.

fluca1978

[quote author="Lukas Geyer" date="1323420960"]Well, QByteArray actually is a BLOB ("The QByteArray class provides an array of bytes."), so why should it be stored as anything else then a BLOB?[/quote]

Correct, even if this example they are not Large...sounds as they should be stored as BOB! Just joking.