set the top 10 and calculate yesteraday sum of theire yesterday price

[#1]

Hi everyone,

I have a table like the table at the bellow  in my QV file, data comes from a database by query.

I need to create a simple chart that shows the every day top10 buyers for current day and all the past days in the year, with their yesterday price and WOW price as well, at the top of the bars in bar chart. I don't want to use of individual query in this case. I tried to use of the QV functions and its other ability in order to set the top 10 and also calculate their yesterday's price. can some one let me know how can I do that in QV? (mentioned again ; the solution has to works for all the days in the year, current day and the passed days.)

date	buyer	price
9/1/2012	a	50$
9/1/2012	b	100$
9/1/2012	c	250$
9/1/2012	d	30$
9/1/2012	e	0$
9/1/2012	f	70$
9/1/2012	g	20$
9/1/2012	h	250$
9/1/2012	i	800$
9/1/2012	j	5$
9/1/2012	k	65$
9/1/2012	l	45$
9/2/2012	a	200$
9/2/2012	b	100$
9/2/2012	c	0$
9/2/2012	d	300$
9/2/2012	e	150$
9/2/2012	f	60$
9/2/2012	g	80$
9/2/2012	h	15$
9/2/2012	i	20$
9/2/2012	j	85$
9/2/2012	k	55$
9/2/2012	l	5$
9/2/2012	m	45$
9/2/2012	n	450$
9/2/2012	o	500$

Thanks,

Nasim