QSqlQuery and SQL text field escape sequences

  • Hi all,

    I need to create "partial" SQL requests which only contains the "value" part.
    I some of those values there are text fields.
    I known, QSqlQuery can handle this very nicely using prepare() and bindValue().
    But is there a way to get the generated SQL query?

    I just need the SQL query string, not to execute the query.
    How can I achieve this?

    Best regards

  • Moderators

  • QSqlQuery::lastQuery() is not working, it returns the SQL query with the place holders, not the full query!

  • Qt Champions 2018

    from qsqlresult.cpp

    QString query = lastQuery();
    if (d->binds == NamedBinding) {
            int i;
            QVariant val;
            QString holder;
            for (i = d->holders.count() - 1; i >= 0; --i) {
                holder = d->holders.at(i).holderName;
                val = d->values.value(d->indexes.value(holder).value(0,-1));
                QSqlField f(QLatin1String(""), val.type());
                query = query.replace(d->holders.at(i).holderPos,
                                       holder.length(), driver()->formatValue(f));
        } else {
            QString val;
            int i = 0;
            int idx = 0;
            for (idx = 0; idx < d->values.count(); ++idx) {
                i = query.indexOf(QLatin1Char('?'), i);
                if (i == -1)
                QVariant var = d->values.value(idx);
                QSqlField f(QLatin1String(""), var.type());
                if (var.isNull())
                val = driver()->formatValue(f);
                query = query.replace(i, 1, driver()->formatValue(f));
                i += val.length();

    It's not trivial but you can probably achieve it without accessing the private API either

  • @VRonin Thank's a lot! You save my day.

    In fact, it is easy, just setup a QSqlField, get the DB driver from QSqlDataBase, and call formatValue().

    QSqlDataBase db = QSqlDatabase::addDatabase(...)
    QSqlField f(QLatin1String(""), QVariant::String);
    f.setValue("The string to be converted");
    QString formatedValue = db->driver()->formatValue(f);

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