query-equivalence

Consider the following relational schema. Students( rollno: integer, sname: string) Courses( courseno: integer, cname: string) Registration( rollno: integer, courseno: integer, per...

Let R and S be two relations with the following schema R ( P , Q , R1, R2, R3) S ( P , Q , S1, S2) Where {P, Q} is the key for both schemas. Which of the following queries are equi...

Consider the following SQL query: Select distinct a 1 , a 2 , ..., a n From r 1 , r 2 , ..., r m Where P; For an arbitrary predicate P, this query is equivalent to which of the fol...