Re: string cast/compare broken?

From: "Zeugswetter Andreas SB SD" <ZeugswetterA(at)spardat(dot)at>
To: "Hannu Krosing" <hannu(at)tm(dot)ee>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Scott Royston" <scroyston(at)mac(dot)com>, <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: string cast/compare broken?
Date: 2002-07-12 07:35:26
Message-ID: 46C15C39FEB2C44BA555E356FBCD6FA4961E1C@m0114.s-mxs.net
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> I guess the strangest part was that both a.foo = 'S' and b.foo = 'S' but
> not a.foo=b.foo; (a.foo is varchar(5) , b.foo is char(5) )
>
> I guess that tha 'S' that b.foo gets compared to is converted to 'S '
> before comparison but when comparing varchar(5) and char(5) they are
> both compared by converting them to varchar which keeps the trailing
> spaces from char(5).

Yes, I think this is inconvenient/unintuitive. If it is doable according to
standards, this should imho be fixed.

> If the conversion where varchar(5) --> char(5) then
> they would compare equal.

I am not sure, since, if the varchar stored 'S ' then the comparison to a char 'S'
should probably still fail, since those spaces in the varchar are significant.
Informix compares them equal, so I guess argumentation can be made in that direction
too (that currently evades my understanding of intuitive reasoning :-).

Andreas

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