Theorem Proving and Database Querying
By Sergei Savchenko
Dr. Dobb's Journal August 1998
<b>(a)</b> (c>'1')A = c e : 2 2 : 3 3 : <b>(b)</b> A= c e : 1 1 : 1 2 : 2 2 : 3 3 : B= x y : 1 9 : 2 8 : 4 9 : <A[cx]B>= c e y : 1 1 9 : 1 2 9 : 2 2 8 : <b>(c) </b> (c>'1')<A[cx]B>= c e y : 2 2 8 :
Example 1: (a) Finding the tuples of A; (b) joining the relations A and B along fields c and x; (c) combining (a) and (b).
Copyright © 1998, Dr. Dobb's Journal