请任何人都可以帮助将以下两个SQL语句转换为Relational Algebra
1)
SELECT D.Dname
FROM Employee E, Department D
WHERE E.Dno = D.Dno
AND E.Lname='Smith'
AND S.Fname='John'
2)
SELECT B.Town
FROM Staff S, Branch B
WHERE S.BranchId = B.BranchId
AND S.lName='Pincher'
AND S.fName='Penny'
答案 0 :(得分:4)
......我想你的意思是WHERE子句中的D.Fname ='John'
答案 1 :(得分:1)
这是第二个SQL语句的关系代数:
π Town (σ lName ='Pincher'^ fName ='Penny'(Staff | x | BranchId Branch))
答案 2 :(得分:0)
π Dname (σ Lname ='Smith'^ Fname ='John'(Employee | x | Dno Department))