From: Craig Ringer <craig@postnewspapers.com.au>
To: novice <user.postgresql@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: count question
Date: Wed, 09 Apr 2008 10:11:39 +0800
Message-ID: <47FC25DB.2090803@postnewspapers.com.au> (raw)
In-Reply-To: <ddcb1c340804081851y245f4776g9de74b5715e3a3e@mail.gmail.com>
References: <ddcb1c340804081851y245f4776g9de74b5715e3a3e@mail.gmail.com>
novice wrote:
> Is it possible to write a query to produce:
>
> meter_id | no_of_bays | bay_id
> ----------+------------+-----------
> 5397 | 2 | 5397-01
> 5397 | 2 | 5397-02
> 5409 | 3 | 5409-01
> 5409 | 3 | 5409-02
> 5409 | 3 | 5409-03
Sure. One way, not necessarily a particularly clever or efficient way,
is to do a join with:
generate_series(1, (select max(no_of_bays) from meter)) as i
and use a WHERE clause to select for `i <= no_of_bays'
eg:
SELECT
meter_id, no_of_bays, meter_id::text||'-'||i::text AS bay_id
FROM meter,
generate_series(1, (select max(no_of_bays) from meter)) as i
WHERE i <= no_of_bays;
--
Craig Ringer
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To: pgsql-sql@postgresql.org
Cc: craig@postnewspapers.com.au, user.postgresql@gmail.com
Subject: Re: count question
In-Reply-To: <47FC25DB.2090803@postnewspapers.com.au>
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