Re: simplifying SQL

Поиск
Список
Период
Сортировка
От Richard Huxton
Тема Re: simplifying SQL
Дата
Msg-id 45CAE46C.7010603@archonet.com
обсуждение исходный текст
Ответ на simplifying SQL  (garry saddington <garry@schoolteachers.co.uk>)
Список pgsql-general
garry saddington wrote:
> I have this query which essentially returns records that exist in one
> table (studentclass) and not another (effortandattainment) to check when
> teachers have entered their student grades.
>
> select

> from studentclass left join effortandattainment

> and studentclass.classid not in (

> I was wondering whether a simpler method exists to do the same thing or
> is this OK.

The formatting on the query isn't great, but I can't quite see what the
"left join" is doing with the "not in" too. I'd probably just have the
left join and check that "effortandattainment.classid IS NULL".

--
   Richard Huxton
   Archonet Ltd

В списке pgsql-general по дате отправления:

Предыдущее
От: Richard Huxton
Дата:
Сообщение: Re: Storing database in cluster (Memory)
Следующее
От: Richard Huxton
Дата:
Сообщение: Re: Persistent dead rows