Re: Relational query with path expressions
From: Tegiri Nenashi <TegiriNenashi_at_gmail.com>
Date: Thu, 2 Apr 2009 21:46:29 -0700 (PDT)
Message-ID: <05154e4e-f89b-47da-aecb-4fb2f735afb8_at_j9g2000prh.googlegroups.com>
Date: Thu, 2 Apr 2009 21:46:29 -0700 (PDT)
Message-ID: <05154e4e-f89b-47da-aecb-4fb2f735afb8_at_j9g2000prh.googlegroups.com>
Granted, if you have a choice between join and generalized projection
you can infer the type of binary operator from the type of operand. In
the expression
x.y
if both are relations, you interpret it as join, and if one is a set
of attributes, than its a projection. That is some economy of
notation, although union, difference, and renaming still have to be