Re: Little question for RDM theoristes
Date: 16 Jun 2006 05:14:21 -0700
Message-ID: <1150460061.078469.57780_at_f6g2000cwb.googlegroups.com>
> Look on this two cases
> 1)After adding new _tuple(s)_ into variables we get new value which is
> result of UNION of two relvalues (first one is previous value,second
> one is set of added tuples).
> 2)After addind new _attribute_ into variables we get new value too
> which is result of carthesian product of two relvalues (first one is
> previous value,second one is unary relation).
>
> There is no difference. In both cases we get new values using peration
> of relational algebra and in both cases these values is ones of the
> same and only type.
I'm afraid I can't explain it any better than I already have.
Compare it with changing the type of a program variable from "int" to "longint" : what arithmetic operator is invoked in doing so ? Received on Fri Jun 16 2006 - 14:14:21 CEST