Qt-interest Archive, October 2007
from sqlite to ulonglong
Message 1 in thread
Hello
I have this test program which puts an quint64 into sqlite and then
retrieves it again to check if it is the same. It doesn't seem to work.
Sqlite converts it to some scientific notation and when i use
toULongLong() to convert it back to a quint64, then it is not the same
value. Apparently qt cannot convert this e notation back. How can I
solve this?
Using Qt 4.3.1.
Best regards,
Tom,
QFile dbfile("testdb.db");
if(dbfile.exists()) dbfile.remove();
QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName(dbfile.fileName());
QCOMPARE(db.open(), true);
QSqlQuery query;
QVERIFY(query.exec("CREATE TABLE r("
"id INTEGER PRIMARY KEY,"
"t_occ INTEGER"
" );"));
quint64 iVeryBig = 0xFFFFFFFFFFFFFFFFLL;
QString str = QString("INSERT INTO r VALUES(0, %1);").arg(iVeryBig);
qDebug() << str;
QVERIFY(query.exec(str));
QVERIFY(query.exec("SELECT t_occ FROM r;"));
while (query.next()) {
bool bOk;
qDebug() << query.value(0).toString();
qDebug() << QString("%1").arg(query.value(0).toULongLong(), 0,
16, QChar('0'));
QCOMPARE(iVeryBig, query.value(0).toULongLong(&bOk));
QVERIFY(bOk);
}
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Message 2 in thread
On October 11, 2007 07:56:03 am Tom Deblauwe wrote:
> Hello
>
> I have this test program which puts an quint64 into sqlite and then
> retrieves it again to check if it is the same. It doesn't seem to work.
> Sqlite converts it to some scientific notation and when i use
> toULongLong() to convert it back to a quint64, then it is not the same
> value. Apparently qt cannot convert this e notation back. How can I
> solve this?
> Using Qt 4.3.1.
> Best regards,
> Tom,
>
> QFile dbfile("testdb.db");
> if(dbfile.exists()) dbfile.remove();
> QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
> db.setDatabaseName(dbfile.fileName());
> QCOMPARE(db.open(), true);
> QSqlQuery query;
> QVERIFY(query.exec("CREATE TABLE r("
> "id INTEGER PRIMARY KEY,"
> "t_occ INTEGER"
> " );"));
> quint64 iVeryBig = 0xFFFFFFFFFFFFFFFFLL;
> QString str = QString("INSERT INTO r VALUES(0, %1);").arg(iVeryBig);
> qDebug() << str;
> QVERIFY(query.exec(str));
>
> QVERIFY(query.exec("SELECT t_occ FROM r;"));
> while (query.next()) {
> bool bOk;
> qDebug() << query.value(0).toString();
> qDebug() << QString("%1").arg(query.value(0).toULongLong(), 0,
> 16, QChar('0'));
> QCOMPARE(iVeryBig, query.value(0).toULongLong(&bOk));
> QVERIFY(bOk);
> }
It looks like Sqlite stores all numeric values as 64-bit floats. That means
that you cannot store 64-bit whole numbers. Looks like the standard way
around this is to store the values as strings. See:
http://www.sqlite.org/datatypes.html
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Message 3 in thread
Chris Thompson wrote:
> It looks like Sqlite stores all numeric values as 64-bit floats. That means
> that you cannot store 64-bit whole numbers. Looks like the standard way
> around this is to store the values as strings. See:
> http://www.sqlite.org/datatypes.htm
Thanks for the information!
Apparently I should just store it as timestamp. I was trying to store it
as a timestamp in milliseconds, but I'll just store it as a date with
date.toString(Qt:ISODate). I can then retrieve it with
query.value(0).toDateTime(), which is what I want anyway. However, I'll
need to add the miliseconds myself to the ISODate which Qt gives me. Or
is there another way?
best regards,
Tom,
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Message 4 in thread
On 10/11/07, Chris Thompson <cthompson@xxxxxxxxxxxxxxx> wrote:
> On October 11, 2007 07:56:03 am Tom Deblauwe wrote:
> > Hello
> >
> > I have this test program which puts an quint64 into sqlite and then
> > retrieves it again to check if it is the same. It doesn't seem to work.
> > Sqlite converts it to some scientific notation and when i use
> > toULongLong() to convert it back to a quint64, then it is not the same
> > value. Apparently qt cannot convert this e notation back. How can I
> > solve this?
> > Using Qt 4.3.1.
> > Best regards,
> > Tom,
> >
> > QFile dbfile("testdb.db");
> > if(dbfile.exists()) dbfile.remove();
> > QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
> > db.setDatabaseName(dbfile.fileName());
> > QCOMPARE(db.open(), true);
> > QSqlQuery query;
> > QVERIFY(query.exec("CREATE TABLE r("
> > "id INTEGER PRIMARY KEY,"
> > "t_occ INTEGER"
> > " );"));
> > quint64 iVeryBig = 0xFFFFFFFFFFFFFFFFLL;
> > QString str = QString("INSERT INTO r VALUES(0, %1);").arg(iVeryBig);
> > qDebug() << str;
> > QVERIFY(query.exec(str));
> >
> > QVERIFY(query.exec("SELECT t_occ FROM r;"));
> > while (query.next()) {
> > bool bOk;
> > qDebug() << query.value(0).toString();
> > qDebug() << QString("%1").arg(query.value(0).toULongLong(), 0,
> > 16, QChar('0'));
> > QCOMPARE(iVeryBig, query.value(0).toULongLong(&bOk));
> > QVERIFY(bOk);
> > }
>
> It looks like Sqlite stores all numeric values as 64-bit floats. That means
> that you cannot store 64-bit whole numbers. Looks like the standard way
> around this is to store the values as strings. See:
> http://www.sqlite.org/datatypes.html
SQLite 2, that is. SQLite 3 supports actual integers up to 8 bytes:
http://www.sqlite.org/datatype3.html
I'm not sure which version Qt uses, but it looks like version 2 given
that this problem is occurring.
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Message 5 in thread
Andrew Medico wrote:
> SQLite 2, that is. SQLite 3 supports actual integers up to 8 bytes:
> http://www.sqlite.org/datatype3.html
>
> I'm not sure which version Qt uses, but it looks like version 2 given
> that this problem is occurring
It is version 3 that Qt uses I'm sure. But... It is a signed integer
which gets stored as those docs say. So my problem was that I was
printing my iVeryBig as an unsigned integer in the SQL statement. If I
make it a qint64 it works.
Thanks,
Best regards,
Tom,
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