On Fri, 2002-07-12 at 08:50, Tom Lane wrote:
> Scott Royston <scroyston@mac.com> writes:
> > [ various examples of comparing char and varchar ]
>
> I see no bug here. For the CHAR datatype, trailing spaces are defined
> to be insignificant. For VARCHAR and TEXT, trailing spaces are
> significant. If you want to compare a CHAR value to a VARCHAR or TEXT
> value, your best bet is a locution like
> rtrim(charval) = varcharval
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). If the conversion where varchar(5) --> char(5) then
they would compare equal.
I vaguely remember something in the standard about cases when comparing
char() types should discard extra spaces.
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Hannu