functional-dependencies

问题 I looked in Decomposing a relation into BCNF answers and tried it on my homework, but i don't get the correct answers, so i ask for help in BCNF decomposition Consider R=(ABCDEG) & F={BG->CD, G->A, CD->AE, C->AG, A->D} . I start pick A->D . Now i got S=(AD), R'=(ABCEG). I pick G->A . Now i got S=(AD,AG) R'=(BCEG) . I pick C->G . Now i think i need to get S=(AD,AG,CG) and R'=(BCE) , But the answer in the end is (AD,AG,CGE,BC) .what went wrong? or perhaps, a better algorithm? 回答1: To convert a

问题 I need closure on this. I fabricated a definition that partial dependency is when fields are indirectly dependent on the primary key or partially dependent but are also dependent on other keys that depend on the primary such that if the field which another field depends on id deleted that field will still exist due to its dependence on the primary key. I am not sure if it is correct. I have researched and every definition sounds misleading.Is my definition correct and if not please explain?