Assume we have two relations R(a,b) and S(b,c). All three attributes (a, b, and c) are integer attributes. Assume that Relation R contains the following tuples: (1,2), (2,3), (4,7) and (3,4). Assume that Relation S contains the following tuples (2,2), (2,3), (4,6) and (7,5). How many tuples are in the result of Natural Join between R and S?

Course: Principles of Database   please solve it within 30 minutes. please please, pleaseThank you Single Choice Questions 11. Given a relation R and a condition f for selecting from relation R, the correct relational algebraic expression is (    ). A、R X R             B、 R ⋈ R        C、sf(R)                 D、 ∏f(R) 12. If relations R and S have a common attribute set Y, when executing , tuples that do not have matching values on attribute Y will be discarded. To avoid discarding those tuples, which operation should be used? (    ) A. Aggregation.                        B. Grouping. C. Outer union.                        D. Outer join. 13. To address the "lost update" problem, a transaction must obtain (    ) before updating a data set. A. Shared lock (S-lock).               B. Exclusive lock (X-lock). C. Shared lock (S-lock) and exclusive lock (X-lock). D. Shared lock (S-lock) or exclusive lock (X-lock). 14. If, during the system operation, data stored on external storage is…

2) A relation schema R is defined tot be in 2NF if every nonprime attribute of R is blank the primary key of R.A) transitively dependent on B) fully functionally dependent onC) a candidate key of D) partially functionally dependent onE) part of

p.609, icon at Example 2 # 2. Let A be the set of all points in the plane with the origin removed. That is, Define a relation on A by the rule: A = {(x, y)|x, y = R} - {(0,0)}. (a, b)R(c, d) ↔ (a, b) and (c, d) lie on the same line through the origin. (a) Prove that R is an equivalence relation. (b) Describe the equivalence classes arising from the equivalence relation R in part (a). (c) If A is replaced by the entire plane, is R an equivalence relation?