Re: columns for count histograms of values

["Mag Gam" <magawake(at)gmail(dot)com>]

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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