8. Example: R3 := R1 × R2 R3( A, R1.B, R2.B, C )‏ R1( A, B )‏ 1 2 5 6 1 2
1 2
3 4
R2( B, C )‏
5 6
7 8
9 10
R3( A, R1.B, R2.B, C )‏

31. Bars name license addr Beers manf name Sells Bars sell some beers.
Note:
license =
beer, full,
none
Beers
manf
name
Sells
Bars sell some
beers.
Frequents
Drinkers frequent
some bars.
Likes
Drinkers like
some beers.
Drinkers
addr
name

46. drinker bar drinker beer
tv tv2
Sally Bud
Sally Joe’s
Likes
Frequents
to output
check these
are equal
check
for Joe

47. Question: Why do we need b1.name < b2.name