1 1 vote If( A->D and D->->C ) => A->-> C Is this implication valid? Databases databases database-normalization + – rahul sharma 5 1.6k views answer comment Share Follow Print See 1 comment 1 1 comment reply joshi_nitish commented Jul 6, 2017 reply Follow flag MVD are not in syllabus right?? 0 0 replyShare Please log in or register to add a comment.
0 0 votes No, this is not valid. Each functional dependency is MVD but not Vice Versa. Suppose if it was as A->D and D->C then A->->C is correct as A->D and D->C implies A->C Manu Thakur answered Jul 6, 2017 Manu Thakur comment Share Follow See all 3 Comments 3 3 Comments reply rahul sharma 5 commented Jul 7, 2017 reply Follow flag I know it is generally false,but i am asking one particular case in question?Can you tell me why the implication is false? –1 –1 replyShare Manu Thakur commented Jul 7, 2017 i edited Jul 7, 2017 reply Follow flag because D->->C doesn't imply that D->C, hence A->C isn't implied too in this particular case. 0 0 replyShare rahul sharma 5 commented Jul 11, 2017 reply Follow flag For every single value of A i have one value of D and for every one value of D i have multi value of C,then i can say that for every value of A there will be multi value of C. I dont see the reason for it to be false. If i say For every every student Id there is a unique phone number. Id -> Phone and then i say for every phone number i have multiple email ids.Then for every student id i will definitely have multiple emails.Please correct me if i am wrong –1 –1 replyShare Please log in or register to add a comment.
