In this specific case, examining your original data, there will be no
records that match your selection criteria. Normally, one would expect
a single record to be returned with a single column that contains a
zero value. Using the GROUP BY changes this, and the query will attempt
to return one record for each "towar" value that matches the selection
criteria; since there are none, no records are returned. When using a
COUNT(*) and a GROUP BY together, one normally includes the GROUP BY
column(s) in the list of columns to be returned.
-ken
On 9-Apr-05, at 1:31 AM, Adam Dziendziel wrote:
[EMAIL PROTECTED] wrote:
COUNT(*) returns NULL if there are no records selected. Change the
query like
this to accomplish what you're looking for:
SELECT COALESCE(COUNT(*), 0)
FROM drzewo_towar
WHERE lft > 13
AND rgt < 14
GROUP BY towar;
Thanks! But it's a bit strange - if I remove "GROUP BY" this query
(executed using sqlite3_get_table()) returns 0. With "GROUP BY" the
number of rows returned by sqlite3_get_table() equals 0 (not 1 with
NULL as I expected).
Adam
