Hi John,
John Sidney-Woollett schreef:
Useful to add a title to your messages before you post...
It escaped before finishing.
How about:
select parentid, count(*) as number_of_children
from childtable
group by parentid
order by parentid;
It works but can you tell me why this works?
You might need to read a good SQL primer to get a full explanation of
this feature.
Reading from the docs,
http://www.postgresql.org/docs/7.4/interactive/sql-select.html
quote
The optional GROUP BY clause has the general form
GROUP BY expression [, ...]
GROUP BY will condense into a single row
