Judgment paradigm level
-
There is a relationship model W(C,P,S,G,T,R), where the meanings of each attribute are: C course, P teacher, S student, G grade, T time, R classroom, according to the definition, there are the following data dependencies Set D={C→P, (S,C)→G, (T,R)→C, (T,P)→R, (T,S)→R}. A candidate key for a relational schema W is _____, and W is normalized up to _____. The correct option is __________.
-
For the management of chain stores, a relationship model is designed: store (store, commodity department, commodity, commodity department manager), the following statement is correct _________.
-
For library management, it is known that a book can only be placed in one room, it can be placed in multiple bookshelves, a bookshelf can hold multiple books, a room has multiple bookshelves, and a room has an administrator. Please analyze the relationship model: Books (book number, title, publication date, publishing house, room number, shelf number, administrator), the correct statement is ____.
-
For equipment management, please analyze the relationship model: equipment (equipment number, equipment name, manufacturer number, manufacturer name, manufacturer address, part number, part name, part price, device price), the correct statement is _______________.
-
For equipment management, please analyze the relationship model: equipment (equipment number, equipment name, manufacturer number, manufacturer name, manufacturer address, part number, part name, part price, device price), the correct statement is _______________.
-
Known relation schema R (A, B, C, D), functional dependency set F={ A->C, DA->B }. Then the correct statement about R is _______________.
-
According to the corresponding functional dependencies, Q: Which of the following relation patterns does not conform to the second normal form is _______.
-
If there is a relational schema R(A, B, C, D, E, F), and its functional dependency set is {E→D, C→B, CE→F, B→A}, then R belongs to the highest normal form_ ________.
-
If there is a relational schema R(A, B, C, D, E), and its functional dependency set is {A→B, CE→A, B→D}, then R belongs to the highest normal form _________.
Find the equivalent minimum dependency set
There is a functional dependency set: F={AB→C, C→A, BC→D, ACD→B, D→EG, BE→C, CG→BD, CE→AG} Calculate its equivalent minimum dependency set
.
Functional dependency set F={D→G, C→A, CD→E, A→B} with relation schema R
(1) Calculation closure D+, C+, A+, (CD)+, (AD)+, (AC)+, (ACD)+.
(2) Find the minimum equivalent dependency set Fm of F
(3) Find the code of R, try to explain which normal form R belongs to?
