From: Emi Lu <emilu@encs.concordia.ca>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Amos Hayes <ahayes@polkaroo.net>
Cc: pgsql-sql@postgresql.org
Subject: Re: Find min and max values across two columns?
Date: Mon, 15 May 2006 17:40:40 -0400
Message-ID: <4468F558.7070407@encs.concordia.ca> (raw)
In-Reply-To: <9558.1143234035@sss.pgh.pa.us>
References: <DAD4674C-1896-4F24-B43B-B884491DB931@polkaroo.net>
<9558.1143234035@sss.pgh.pa.us>
Hello,
I tried "select greatest(max(a), max(b)) from public.test", but I got
the following errors:
ERROR: function greatest(integer, integer) does not exist
HINT: No function matches the given name and argument types. You may
need to add explicit type casts.
May I know where I can read the docs about greatest & least please.
I am using PostgreSQL 8.0.7.
Thanks,
Ying
>Amos Hayes <ahayes@polkaroo.net> writes:
>
>
>>I'm trying to build a query that among other things, returns the
>>minimum and maximum values contained in either of two columns.
>>
>>
>
>I think you might be looking for
>
> select greatest(max(columnA), max(columnB)) from tab;
> select least(min(columnA), min(columnB)) from tab;
>
>greatest/least are relatively new but you can roll your own in
>older PG releases.
>
> regards, tom lane
>
>---------------------------(end of broadcast)---------------------------
>TIP 9: In versions below 8.0, the planner will ignore your desire to
> choose an index scan if your joining column's datatypes do not
> match
>
>
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To: pgsql-sql@postgresql.org
Cc: emilu@encs.concordia.ca, tgl@sss.pgh.pa.us, ahayes@polkaroo.net
Subject: Re: Find min and max values across two columns?
In-Reply-To: <4468F558.7070407@encs.concordia.ca>
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