From: Richard Huxton <dev@archonet.com>
To: PS PS <psus2020@yahoo.com>
To: pgsql-sql@postgresql.org
Subject: Re: One-2-many relation - need distinct counts
Date: Wed, 27 Aug 2003 20:51:26 +0100
Message-ID: <200308272051.26634.dev@archonet.com> (raw)
In-Reply-To: <20030826135458.83369.qmail@web20302.mail.yahoo.com>
References: <20030826135458.83369.qmail@web20302.mail.yahoo.com>
On Tuesday 26 August 2003 14:54, PS PS wrote:
> Select Count(Distinct(account_no))
> from A, B
> where A.Account_no = B.Account_no
>
> I get the correct count. If I do this:
> Select Count(Distinct(account_no)), B.Account_type
> from A, B
> where A.Account_no = B.Account_no
> group by B.Account_type
>
> I get wrong counts because there some are duplicated.
> I tried everything that I can think of - subquery, sub
> table etc. I would appreciate some help in writing
> the query. Thanks in advance.
I'm not sure the query is well formed. If you have the following in B:
Acct_type | Acct_no
alpha | 0001
beta | 0002
alpha | 0003
beta | 0003
I think you're saying you get:
alpha 2
beta 2
Are you saying you want
alpha 2
beta 1
or:
alpha 1
beta 2
If you're not sure which you want, that's the route of your problem. If you
want the first try something like
SELECT account_no, min(account_type) FROM B GROUP BY account_no
--
Richard Huxton
Archonet Ltd
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To: pgsql-sql@postgresql.org
Cc: dev@archonet.com, psus2020@yahoo.com
Subject: Re: One-2-many relation - need distinct counts
In-Reply-To: <200308272051.26634.dev@archonet.com>
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