How to query a local QSqlQueryModel?

Question

I am displaying a QSqlTableModel in QSqlTableModel::OnManualSubmit mode.

I want to run SQL style queries on my local copy, for example I have a getMax function that changes as I add new rows. If my user locally changes the QSqlTableModel during interaction I expect the getMax to produce a different input, but instead the getMax function remotely queries the data and the result will always be the same independent of any changes the user has made.

int TestMe::getMax(QString col,QString table)
{
    QSqlQuery query;
    sf(query.exec("SELECT MAX("+col+") FROM "+table));
    sf(query.first());
    auto rec = query.record();
    return rec.field(0).value().toInt();
}

How do I run queries on my local copy of the model?

@Googie I mean the copy of the remote SQL data that lives in my model as opposed to online in the SQL database on my server. When I submit my model these two will synchronize. — Mikhail, Jan 28 '14 at 00:44
QSqlTableModel implements QAbstractItemModel and therefore it provides standard API for accessing data in it, mainly with QAbstractItemModel::data(). QSqlTableModel delegates SQL query to QSqlQuery. You cannot execute SQL query directly on QSqlQueryModel, because it's not a SQL interpreter. — Googie, Jan 28 '14 at 13:43

score 1 · Accepted Answer · answered Jan 28 '14 at 13:49

QSqlTableModel (or more generally QSqlQueryModel) delegates query execution to QSqlQuery. When results from query are received they are stored internally in form of a table with rows and columns and you can access them using QModelIndex and QAbstractItemModel::data().

QSqlTableModel itself is not SQL interpreter. Not at all. It doesn't provide any analysis routines for you. It isn't the purpose of this class. If you need analysis of data in the model, you have to write it yourself.

How to query a local QSqlQueryModel?

1 Answers1