题目3单选题
设有关系R(A,B,C)和S(C,D),与关系代数表达式<img src="https://tihai-oss-cloud.itihey.com/img/c73567bcff81d19ffe19733661c5803e.png">不等价的SQL语句是哪个A. select A,B,D from R natural join SB. select A,B,D from R,S where R.C=S.CC. select A, B, D from R inner join S on R.C=S.CD. select A,B,D from R full outer join S on R.C=S.C