Given two union compatible relations $R_1(A, B)$ and $R_2 (C, D)$, what is the result of the operation $R_1 \Join_{ A = C \wedge B = D} R_2$?
$R_1 \cup R_2$
$R_1 \times R_2$
$R_1 – R_2$
$R_1 \cap R_2$
This question is an example of Theta Join,
The join here will be selecting only those tuples where A = C and B = D, meaning it is the intersection. D option.
Gatecse