Acquire data from database & Plot it to a graph

[maveric]

hi,

for(int i=q.first();i<q.last();i++)
{
       QList <Double> x_list;
       x_list.append(q.value(i));
       QList <Double> y_list;
       y_list.append(q.value(i));
       m_curve = new QwtPlotCurve();
       m_curve->setPen(QPen(Qt::red));
       m_curve->setData(x_list.value(i), y_list.value(i), 100);
       m_curve->attach(myPlot);
       myPlot->replot();
}

for(int i=q.first();i<q.last();i++)
{
       QList <Double> x_list;
       x_list.append(q.value(i));
       QList <Double> y_list;
       y_list.append(q.value(i));
       m_curve = new QwtPlotCurve();
       m_curve->setPen(QPen(Qt::red));
       m_curve->setData(x_list.value(i), y_list.value(i), 100);
       m_curve->attach(myPlot);
       myPlot->replot();
}

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Actually from the for loop i am explaining

taking a incremental value i and initializing that to the first value present in the query

QSqlQuery q("SELECT xval,yval FROM PlotGraph1");

this is the query which displays the values present in the database..

taking a qlist and x_list which takes the x values present in the database...
assigning the values present in the database to x and y...

here x_list is being appended with the values of xval (first field) present in the database..

QList <double> x_list;
x_list.append(q.value(i));

similarlly
here y_list is being appended with the values of yval (second field) present in the database..

QList <double> y_list;
y_list.append(q.value(i));

Next

m_curve = new QwtPlotCurve();
m_curve->setPen(QPen(Qt::red));
m_curve->setData(x_list.value(i), y_list.value(i), 100);
m_curve->attach(myPlot);
myPlot->replot();

now i am initializing a curve as m_curve
taking red color to plot my curve, i initialized a pen over here..


m_curve->setData(x_list.value(i), y_list.value(i), 100);
this actually takes the values present in the x_list and y_list ..

now

m_curve->attach(myPlot);
myPlot->replot();

the above code will attach my curve to my qwtplot widget ie..(myPlot)
and plots the points based on the values taken above...


i kept this code in draw function and keep on calling @ 1sec rate with the timer....


I think i have explained every thing present in the code....

if i go wrong any where please correct me so that i will not repeat the mistake again...



thanks in advance...

giving or taking, both r the similar form's of getting knowledge...