Posted by Gordon Burditt on 07/01/07 18:47

>Constructed a fairly big table with 20 rows, most of which are
>TINYINTs based on user selection for a dropdown box. This is the form:
>
>http://www.threechords.org/spb/survey/
>
>Each field obviously corresponds to a row in the table, and the
>majority are integers indicating the user's selection.

This doesn't really have that much to do with PHP; it's more related to
SQL and databases in general.

>My issue is how to do meaningful stuff with the stored data. I believe
>I need to use GROUP BY functionality but I'm not certain - how can I
>calculate, say, the number of "1" ('Excellent') values for the field
>"writing_quality"?

select count(*) from survey where writing_quality=1;

If you want the whole distribution of votes:

select writing_quality, count(writing_quality) from survey group by writing_quality;

which will get you a list of writing_quality values and the number
of votes that gave that value, e.g.:

writing_quality count(writing_quality)
1 32
2 86
3 74
4 50
5 22
7 1

(note: it seems nobody voted "6", so it is not listed).

If you want an overall average:

select avg(writing_quality) from survey;

which might give you 2.8 as an average.

You can also try things like:

select avg(writing_quality) from survey where sex = 'Male' and age >= 20 and age < 30;

which gives you a score from a specific segment of your users.

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