Re: COUNT and GROUP BY performing strangely

http://stackoverflow.com/questions/2054235/why-doesnt-postgres-group-by-null-select-counts
http://www.postgresql.org/docs/9.0/static/functions-aggregate.html
says "number of input rows for which the value ofexpression is not null"

On Fri, Oct 25, 2013 at 3:38 PM, James David Smith <
james(dot)david(dot)smith(at)gmail(dot)com> wrote:

> Hi everyone,
>
> Any thoughts on the below three queries please?
>
> james_traffic=# SELECT count(*) FROM stage;
> count
> --------
> 430991
> (1 row)
>
> james_traffic=# SELECT bad_flag, count(bad_flag) FROM stage GROUP BY
> bad_flag;
> bad_flag | count
> ----------+-------
> | 0
> 1 | 4102
> (2 rows)
>
> james_traffic=# SELECT count(bad_flag) FROM stage;
> count
> -------
> 4102
> (1 row)
>
> I'm confused as to why the second query doesn't return this:
>
> bad_flag | count
> --------------+-------
> | 426889
> 1 | 4102
>
> It should count the records surely, even if the field is blank/null ?
>
> Thanks
>
> James
>
>
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