)
David J
From: pgsql-general-ow...@postgresql.org
[mailto:pgsql-general-ow...@postgresql.org] On Behalf Of Alpha Beta
Sent: Tuesday, February 15, 2011 5:01 PM
To: pgsql-general@postgresql.org
Subject: [GENERAL] subset of attributes
Hi,
while reading about databases, I didn't under
On 02/15/11 2:01 PM, Alpha Beta wrote:
Hi,
while reading about databases, I didn't understand what can be subset
of attributes, see the following :
Let Ri (Xi) be a relation sheme, where Xi is a set of attributes. and
if t is a tuple for Ri (Xi) and Y is a subset of Xi, then t[Y] denote
th
Hi,
while reading about databases, I didn't understand what can be subset of
attributes, see the following :
Let Ri (Xi) be a relation sheme, where Xi is a set of attributes. and if t
is a tuple for Ri (Xi) and Y is a subset of Xi, then t[Y] denote the
subtuple of t corresponding to Y.
does a s
