Recent questions tagged goclasses-databases-practice-questions

Which of the following statements are always true?For any attribute set $X$, $(X^+)^+=X^+$. Every relation schema having exactly two attributes is in BCNF. If $AB \to C$ ...

Consider $R(A,B,C,D,E)$ with $A \to B,$ $BC \to E,$ and $ED \to A$.Which of the following statements are correct?$ACD$ is a candidate key. $BCD$ is a candidate key. $CDE$...

Consider $R(A,B,C,D,E,F)$ with $AC \to B,$ $BD \to F,$ and $F \to CE$.Which functional dependency causes $R$ to violate $\text{3NF}$?$AC \to B$ $BD \to F$ $F \to C$ $F \t...

Consider $R(A,B,C,D,E)$ with $C \to D,$ $DE \to B,$ and $AB \to C$.Which of the following statements are correct?$ABE$ is a candidate key. $ACE$ is a candidate key. $ADE$...

Consider $R(A,B,C,D,E)$ with $A \to B,$ $B \to C,$ $C \to D,$ and $C \to E$.Assuming atomic attribute values, what is the highest normal form satisfied by $R$?$\text{1NF}...

Consider $R(A,B,C,D)$ with functional dependencies $AB \to C,$ $BC \to D$.Which statement correctly explains why $R$ is not in $\textbf{3NF}$?$AB \to C$ violates $\text{3...

Consider the relation $R(A,B,C,D,E)$ with functional dependencies $AB \to C$, $E \to D$.Assume that no other non-trivial functional dependencies hold and that all attribu...

What is the name of the type of functional dependency that is removed when converting a relation from $\text{2NF}$ to $\text{3NF}$?Partial dependency Transitive dependenc...

Consider relation $\text{Exam(ExamId, Section, Date, Duration, AnswersDate, AnswersTime, RoomId, TimeFrom, RoomNo)}$ with primary key $\text{(ExamId, Section)}$ and the f...

Consider the relation $R(V,W,X,Y,Z)$ with functional dependencies :$V \to X$$WY \to X$$VWY \to Z$The candidate key is $VWY$.Assume that all attributes contain atomic valu...

Consider the relation $\text{course(c_id, dept_id, dept, evaluations, inst, office, sect, time_slot)}$with the following sample tuple:$\text{(61, 1, CS, {HW, Midterm, Fin...

Consider the two FD sets, $F=\{A \to B,\ B \to C,\ C \to A\}$ and $G=\{A \to C,\ C \to B,\ B \to A\}$.Which of the following statements is correct?Only $F$ is a minimal c...

Consider $F=\{AB \to CF,\ CD \to EA,\ E \to ABC,\ B \to F,\ C \to D\}$Which of the following is a minimal cover of $F$?$\{AB \to C,\ C \to D,\ C \to E,\ E \to A,\ E \to B...

Consider $F=\{P \to S,\ PQ \to ST,\ S \to RU,\ RU \to S,\ PT \to V\}$.Which of the following is a minimal cover of $F$?$\{P \to S,\ PQ \to ST,\ S \to RU,\ RU \to S,\ PT \...

Consider $F=\{A \to B,\ AB \to C\}$.Which of the following statements is correct?$B$ is extraneous in the left-hand side of $AB \to C$. $A$ is extraneous in the left-hand...

Consider the following two sets of functional dependencies:$F=\{A \to B,\ B \to C\}$$G=\{A \to B,\ B \to C,\ A \to C\}$Which of the following statements are correct?$F$ c...

Consider the relation schema $R(A,B,C,D,E)$ with $F=\{AB \to D,\ AC \to E,\ A \to B,\ BC \to E,\ A \to E\}$.Consider the following functional dependencies:$A \to D$$AC \t...

Consider the relation schema $R(A,B,C,E,F,G,H)$ with $F=\{A \to BC,\ C \to FG,\ E \to HG,\ G \to A\}$Which of the following statements are correct?$A^+=\{A,B,C,F,G\}$ $A ...

Consider the relation schema $R(A,B,C,D,E)$ with$F=\{AB \to C,\ CD \to E,\ DE \to B\}$Which attributes must necessarily occur in every candidate key of $R$?$A$ $B$ $C$ $D...

Consider the relation$Student(S,I,E,N,L)$with the functional dependencies$F=\{S \to I,\ I \to E,\ E \to S,\ N \to L\}$Which of the following are candidate keys?$SN$ $IN$ ...

Consider the relation schema $R(A,B,C,D,E,F)$ with$F=\{BE \to C,\ B \to F,\ D \to F,\ AEF \to B,\ A \to E\}$Which of the following is a candidate key of $R$?$ACD$ $AD$ $F...

Consider the relation schema $R(A,B,C,D,E,F)$ with the functional dependencies$F=\{A \to BF,\ B \to F,\ CD \to E,\ DE \to F\}$.What is $(CD)^+$?$\{C,D,E\}$ $\{C,D,E,F\}$ ...

Suppose $R(A,B,C)$ satisfies $AB \to C$ and $B \to C$.Which of the following two-tuple relation instances is a valid counterexample showing that $A \to C$ does not necess...

Suppose the following functional dependencies hold on $R(A,B,C,D)$:$A \to B$$B \to C$Which of the following functional dependencies must also hold?$A \to C$ $AC \to B$ $C...

Consider the relation schema $R(A,B,C,D)$.Which of the following are trivial functional dependencies?$AB \to A$ $A \to AB$ $ABC \to BC$ $CD \to D$ $B \to C$

Consider a relation schema $R(A,B,C)$.Which of the following statements are correct?If one legal instance of $R$ satisfies $A \to B$, then $A \to B$ must hold as a functi...

Consider the following schema:$\text{Parent(pid ~INTEGER ~PRIMARY KEY)}$$\text{Child(cid ~INTEGER, ~pid ~INTEGER,}$$\text{PRIMARY KEY(cid,~pid),}$$\text{FOREIGN KEY(pid) ...

Consider relation $S(D,E)$ with primary key $(D,E)$.The current instance of $S$ contains $(1,3)$, $(2,4)$, $(3,1)$.Relation $R(A,B,C)$ contains the foreign-key constraint...

Consider the relations $\text{Employee}(eid)$, $\text{Policy}(pid,eid)$, $\text{Dependent}(did,pid)$.The following foreign keys are defined:$\text{Policy}.eid$ $\text{ RE...

Consider the relations $Parent(pid)$ and $Child(cid,pid)$where $Parent.pid$ is the primary key and $Child.pid$ is a foreign key referencing $Parent.pid$No cascading actio...