Given two relation schemas R = (A, B, C), and S = (D, E, F), and two relations r(R) and s(S), write SQL queries that produce identical results to the following relational algebra expressions. Recall that r and s are sets of tuples, not multisets, and the results of these operations should also be sets of tuples. Therefore, you should eliminate duplicates where necessary, but only do this where it is actually necessary! Feel free to explain your rationale in the comments.

1. A(r) 2. B=17(r) 3. r s 4. A,F(C=D(r s))

For these problems, R = (A, B, C) as before, and let there be two relations r1(R) and r2(R). Write complete SQL queries (not SQL fragments) that produce identical results to these relational algebra expressions. Again, consider that the inputs are sets of tuples, and the results must also be sets of tuples. 5. r1 U r2 6. r1 n r2 7. r1-r2