# 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.

R := R EXTEND someexpression AS someattributename.

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