Question about method named rowCount() of QSqlTableModel

[silentyears]

Hi all,
After i use QSqlTableModel to get one table in database, i want to handle every row in table ,so i code as follows:


QSqlTableModel tableModel;
tableModel->setTable(tableA);
tableModel->select();
int nCount = tableModel->rowCount();
for(int i=0, i<nCount, i++)
{
// handle every row
// ....
}

here is my question, why the value of nCount is less than the real rows' count(Observed from database table view)? And the value is 256, could i get whole rows when the count of rows are so many like tens of thousands? Or is there any smarter idea to do the same work?
Thank you!

[StrikeByte]

it is possible that nCount is different than the real rows in the database (this behaviour is described in the manual)
from the manual:
If the database supports returning the size of a query (see QSqlDriver::hasFeature()), the number of rows of the current query is returned. Otherwise, returns the number of rows currently cached on the client.

if there is a smarter way, depends on what you try to accomplish

[silentyears]

it is possible that nCount is different than the real rows in the database (this behaviour is described in the manual)
from the manual:
If the database supports returning the size of a query (see QSqlDriver::hasFeature()), the number of rows of the current query is returned. Otherwise, returns the number of rows currently cached on the client.

if there is a smarter way, depends on what you try to accomplish

Thank you so much!
could you tell me where the behaviour is described ? i can't find in the help doc, maybe i'm not careful enough.
I use Oracle database, if it supports returning the size of a query and how?
I also think if i can change the cached to get more number of rows, but it doesn't seem a good way...

Thx again!

[StrikeByte]

The behaviour is described in http://qt-project.org/doc/qt-4.8/qsqlquerymodel.html#rowCount
To see if it supports returning the size you can use the hasFeature() function (there is a link to the function in the rowcount documentation)
To get all rows you can do a sql select that returns all rows (SELECT * FROM tablename) you can replace * with a column name u need

If you don't mind me asking why do you want to get a count of all rows?

[silentyears]

The behaviour is described in http://qt-project.org/doc/qt-4.8/qsqlquerymodel.html#rowCount
To see if it supports returning the size you can use the hasFeature() function (there is a link to the function in the rowcount documentation)
To get all rows you can do a sql select that returns all rows (SELECT * FROM tablename) you can replace * with a column name u need

If you don't mind me asking why do you want to get a count of all rows?
Thank you first！ sorry for reply late，I just see it。
To get all rows，I can handle every row though a loop（eg· for（int i=0；i<rowcount；i++））
Is there any better idea to traverse a table without rowcount of qsqltablemodel？thanks！

[anda_skoa]

You can use QSqlQuery directly.

Cheers,
_