Re: columns for count histograms of values

Just curious, how are you planning to display the histogram?
Are you allowed to use application code (C/C++/Perl, etc..) to generate the
histogram? Personally, SQL is great for showing the data but not good for
making graphs with data you can show.

On Wed, Apr 30, 2008 at 5:01 PM, Alexy Khrabrov <deliverable(at)gmail(dot)com>
wrote:

> Greetings -- I have a table of the kind
>
> Ratings:
> id integer
> rating smallint
>
> -- where value can take any value in the range 1 to 5. Now I want to have
> a statistical table Stats of the form
>
> id integer
> min smallint
> max smallint
> avg real
> r1 integer
> r2 integer
> r3 integer
> r4 integer
> r5 integer
>
> -- how can I create it in one pass over Ratings? I can use min(), max(),
> avg() for
> insert into stats values (id,select min(rating), max(rating), avg(rating),
> ...) from ratings
>
> -- but what to do for r1,..,r5, short of subselects (select count(rating)
> from ratings where stats.id=ratings.id) for each, which is an overkill?
>
> Also, if a table Stats already exists with some more columns, and we need
> to do an update, not insert, for the above, how would that work --
>
> update stats set min=min(ratings), ... from ratings where stats.id=
> ratings.id -- how do we do the histogram in this case, where the id is
> fixed explicitly?
>
> Cheers,
> Alexy
>
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