From: | "Dave Page" <dpage(at)vale-housing(dot)co(dot)uk> |
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To: | <apache(at)cosinus(dot)sederhana(dot)or(dot)id>, "pgadmin-hackers" <pgadmin-hackers(at)postgresql(dot)org> |
Subject: | Re: translator |
Date: | 2003-07-03 19:05:07 |
Message-ID: | 03AF4E498C591348A42FC93DEA9661B83AF15D@mail.vale-housing.co.uk |
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Lists: | pgadmin-hackers |
> -----Original Message-----
> From: Erwien Samantha Y [mailto:apache(at)cosinus(dot)sederhana(dot)or(dot)id]
> Sent: 03 July 2003 17:32
> To: pgadmin-hackers
> Subject: Re: [pgadmin-hackers] translator
>
>
> What is the correct definition of "Cast" and "Aggregate" in PostgreSQL
Off the top of my head:
Cast - A special type of function used to convert from one datatype to
another e.g. int4 -> text. May be used implicitly i.e. PostgreSQL will
automatically use it when required, or explicitly i.e. you write a query
such as SELECT 23::text;
Aggregate - A function (sometimes functions) that return a single result
from a group of values - for example SELECT max(foo) FROM bar; will
return a single value which is the maximum value found in the foo column
in the bar table. Other aggregates include min() (minimum) and avg()
(average).
Regards, Dave.
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