# Recent questions tagged database-normalization

1 vote
1 answer 16 views
It is 2NF or not ? Just explain this portion.
0 votes
1 answer 611 views
Suppose the following functional dependencies hold on a relation $U$ with attributes $P,Q,R,S$, and $T$: $P \rightarrow QR$ $RS \rightarrow T$ Which of the following functional dependencies can be inferred from the above functional dependencies? $PS \rightarrow T$ $R \rightarrow T$ $P \rightarrow R$ $PS \rightarrow Q$
1 vote
5 answers 928 views
Consider the relation $R(P,Q,S,T,X,Y,Z,W)$ with the following functional dependencies. $PQ\rightarrow X;\quad P\rightarrow YX;\quad Q\rightarrow Y; \quad Y\rightarrow ZW$ Consider the decomposition of the relation $R$ into the constituent relations according to ... , but $D_2$ is a lossless decomposition Both $D_1$ and $D_2$ are lossless decompositions Both $D_1$ and $D_2$ are lossy decompositions
0 votes
1 answer 48 views
Given relation R(a,b,c,d,e,f,g). Functional dependencies are as follows:- { a → b,d,e,g c,d → f f → c e,g → d } What is the highest normal form?
0 votes
0 answers 10 views
The answer given is C but I don’t understand. I think B has partial dependency because attribute set X which has some attributes from the key set determines the attribute set A.
0 votes
1 answer 43 views
Consider a relation $R(X,Y,Z)$ and following functional dependencies set $F$ $X\rightarrow Y$ $Y\rightarrow Z$ How many FD are there in $F^{+}?$
0 votes
1 answer 46 views
Relation R(M,N,O,P,Q) and holding following FD’s F = { M → NO, OP → Q, MO → Q, N → P, Q → MN }, find number of candidate keys and highest normal form. Acc to me all are prime attributes after finding candidate keys but i am not able to decide highest NF
0 votes
0 answers 13 views
$R(A,B,C,D)$ is a relation. Which of the following does not have a lossless join, dependency preserving $BCNF$ decomposition? $A \rightarrow B, B \rightarrow CD$ $A \rightarrow B, B \rightarrow C, C \rightarrow D$ $AB \rightarrow C, C \rightarrow AD$ $A \rightarrow BCD$
0 votes
1 answer 16 views
Let $R (A, B, C, D)$ be a relational schema with the following functional dependencies : $A → B$, $B → C$, $C → D$ and $D → B$. The decomposition of $R$ into $(A, B), (B, C), (B, D)$ gives a lossless join, and is ... gives a lossless join, but is not dependency preserving does not give a lossless join, but is dependency preserving does not give a lossless join and is not dependency preserving
0 votes
0 answers 14 views
Consider the schema $R=(S,T, U, V)$ and the dependencies $S \rightarrow T, T \rightarrow U, U \rightarrow V$ and $V \rightarrow S$. Let $R = (R1\text{ and } R2)$ be a decomposition such that $R1 \cap R2 \neq \phi$. The decomposition is not in $2NF$ in $2NF$ but not $3NF$ in $3NF$ but not in $2NF$ in both $2NF$ and $3NF$
1 vote
1 answer 16 views
Consider the following relational schemes for a library database: Book (Title, Author, Catalog_no, Publisher, Year, Price) Collection(Title, Author, Catalog_no) with the following functional dependencies: $\text{Title Author }\rightarrow\text{ Catalog_no}$ ... are in $3NF$ only Book is in $2NF$ and Collection in $3NF$ Both Book and Collection are in $2NF$ only
0 votes
0 answers 21 views
Consider the following relational schema: $\text{Suppliers}(\underline{\text{sid:integer}},\text{ sname:string, city:string, street:string})$ $\text{Parts}(\underline{\text{pid:integer}}, \text{ pname:string, color:string})$ ... is in $3NF$ but not in $\text{BCNF}$ The schema is in $2NF$ but not in $3NF$ The schema is not in $2NF$
0 votes
0 answers 13 views
Consider the following database relations containing the attributes Book_id Subject_Category_of_book Name_of_Author Nationality_of_Author With Book_id as the primary key. What is the highest normal form satisfied by this relation? Suppose the attributes Book_title and Author_address are ... is changed to {Name_of_Author, Book_title}, what will be the highest normal form satisfied by the relation?
0 votes
0 answers 9 views
Which one of the following statements is $\text{FALSE}$? Any relation with two attributes is in $\text{BCNF}$ A relation in which every key has only one attribute is in $2NF$ A prime attribute can be transitively dependent on a key in a $3NF$ relation A prime attribute can be transitively dependent on a key in a $\text{BCNF}$ relation
0 votes
0 answers 13 views
A database of research articles in a journal uses the following schema. $\text{(VOLUME, NUMBER, STARTPAGE, ENDPAGE, TITLE, YEAR, PRICE)}$ The primary key is '$\text{(VOLUME, NUMBER, STARTPAGE, ENDPAGE)}$ ... the weakest normal form that the new database satisfies, but the old one does not? $1NF$ $2NF$ $3NF$ $\text{BCNF}$
1 vote
1 answer 18 views
A relation $\text{Empdtl}$ is defined with attributes empcode (unique), name, street, city, state and pincode. For any pincode, there is only one city and state. Also, for any given street, city and state, there is just one pincode. In normalization terms, $\text{Empdtl}$ ... in $1NF$ $3NF$ and hence also in $2NF$ and $1NF$ $\text{BCNF}$ and hence also in $3NF$, $2NF$ and $1NF$
0 votes
0 answers 12 views
Relation $R$ with an associated set of functional dependencies, $F$, is decomposed into $\text{BCNF}$. The redundancy (arising out of functional dependencies) in the resulting set of relations is Zero More than zero but less than that of an equivalent $3NF$ decomposition Proportional to the size of F+ Indeterminate
0 votes
0 answers 9 views
Relation $R$ has eight attributes $\text{ABCDEFGH}$. Fields of $R$ contain only atomic values. $F$= $\text{{CH→G, A→BC, B→CFH, E→A, F→EG}}$ is a set of functional dependencies $(FDs)$ so that $F^+$ is exactly the set of $FDs$ that hold for $R$. How many candidate keys does the relation $R$ have? $3$ $4$ $5$ $6$
0 votes
0 answers 11 views
The relation scheme $\text{Student Performance (name, courseNo, rollNo, grade)}$ has the following functional dependencies: name, courseNo, $\rightarrow$ grade rollNo, courseNo $\rightarrow$ grade name $\rightarrow$ rollNo rollNo $\rightarrow$ name The highest normal form of this relation scheme is $2NF$ $3NF$ $\text{BCNF}$ $4NF$
1 vote
1 answer 13 views
From the following instance of a relation schema $R(A,B,C)$ ... $B$ does not functionally determine $C$ $B$ does not functionally determine $C$ $A$ does not functionally determine $B$ and $B$ does not functionally determine $C$
1 vote
1 answer 25 views
The following functional dependencies hold true for the relational schema $R\left \{V,W,X,Y,Z \right \}$: V $\rightarrow$ W VW $\rightarrow$ X Y $\rightarrow$ VX Y $\rightarrow$ ... $\rightarrow$ Z V $\rightarrow$ W W $\rightarrow$ X Y $\rightarrow$ V Y $\rightarrow$ X Y $\rightarrow$ Z
1 vote
1 answer 24 views
For a database relation $R(a, b, c, d)$, where the domains $a, b, c, d$ include only atomic values, only the following functional dependencies and those that can be inferred from them hold $a \rightarrow c$ $b \rightarrow d$ This relation is in first normal form but not in second normal form in second normal form but not in first normal form in third normal form none of the above
1 vote
1 answer 16 views
Consider the following functional dependencies in a database. ... , Age) is in second normal form but not in third normal form in third normal form but not in BCNF in BCNF in none of the above
0 votes
1 answer 15 views
Consider the following implications relating to functional and multivalued dependencies given below, which may or may not be correct. if $A \rightarrow \rightarrow B$ and $A \rightarrow \rightarrow C$ then $A \rightarrow \rightarrow BC$ if $A \rightarrow B$ and $A \rightarrow C$ then ... $A \rightarrow \rightarrow C$ Exactly how many of the above implications are valid? $0$ $1$ $2$ $3$
0 votes
0 answers 13 views
Given the following two statements: S1: Every table with two single-valued attributes is in 1NF, 2NF, 3NF and BCNF. S2: $AB \to C$, $D \to E$, $E \to C$ is a minimal cover for the set of functional dependencies $AB \to C$, $D \to E$, $AB \to E$, $E \to C$. ... one of the following is CORRECT? S1 is TRUE and S2 is FALSE. Both S1 and S2 are TRUE. S1 is FALSE and S2 is TRUE. Both S1 and S2 are FALSE.
0 votes
0 answers 11 views
Consider the relation $X(P,Q,R,S,T,U)$ with the following set of functional dependencies $F = \{ \\ \; \; \{P, R\} \rightarrow \{S, T\}, \\ \; \; \{P, S, U\} \rightarrow \{Q, R\} \\ \; \}$ Which of the following is the trivial functional dependency in $F^+$, where $F^+$ is closure ... $\{P, R\} \rightarrow \{R, T\}$ $\{P, S\} \rightarrow \{S\}$ $\{P, S, U\} \rightarrow \{Q\}$
0 votes
0 answers 7 views
The following functional dependencies hold for relations $R(A, B, C)$ and $S(B, D, E).$ $B \to A$ $A \to C$ The relation $R$ contains $200$ tuples and the relation $S$ contains $100$ tuples. What is the maximum number of tuples possible in the natural join $R \bowtie S$? $100$ $200$ $300$ $2000$
0 votes
0 answers 7 views
Which one of the following statements about normal forms is $\text{FALSE}?$ $\text{BCNF}$ is stricter than $3NF$ Lossless, dependency-preserving decomposition into $3NF$ is always possible Lossless, dependency-preserving decomposition into $\text{BCNF}$ is always possible Any relation with two attributes is in $\text{BCNF}$
0 votes
0 answers 9 views
Consider the following four relational schemas. For each schema , all non-trivial functional dependencies are listed, The bolded attributes are the respective primary keys. Schema I: Registration(rollno, courses) Field courses' is a set-valued attribute containing the set of courses ... Which one of the relational schemas above is in 3NF but not in BCNF? Schema I Schema II Schema III Schema IV
0 votes
0 answers 11 views
For relation R=(L, M, N, O, P), the following dependencies hold: $M \rightarrow O,$ $NO \rightarrow P,$ $P \rightarrow L$ and $L \rightarrow MN$ R is decomposed into R1 = (L, M, N, P) and R2 = (M, O). Is the above ... . Is the above decomposition dependency-preserving? If not, list all the dependencies that are not preserved. What is the highest normal form satisfied by the above decomposition?
0 votes
0 answers 14 views
Which of the following is TRUE? Every relation in 3NF is also in BCNF A relation R is in 3NF if every non-prime attribute of R is fully functionally dependent on every key of R Every relation in BCNF is also in 3NF No relation can be in both BCNF and 3NF
0 votes
0 answers 10 views
Relation $R$ is decomposed using a set of functional dependencies, $F$, and relation $S$ is decomposed using another set of functional dependencies, $G$. One decomposition is definitely $\text{BCNF}$, the other is definitely $3NF$, but it is not known which ... (Assume that the closures of $F$ and $G$ are available). Dependency-preservation Lossless-join $\text{BCNF}$ definition $3NF$ definition
1 vote
1 answer 13 views
Given the following relation instance. ... $Z \rightarrow Y$ $YZ \rightarrow X$ and $Y \rightarrow Z$ $YZ \rightarrow X$ and $X \rightarrow Z$ $XZ \rightarrow Y$ and $Y \rightarrow X$
0 votes
1 answer 12 views
Let the set of functional dependencies $F=\{QR \rightarrow S, \: R \rightarrow P, \: S \rightarrow Q \}$ hold on a relation schema $X=(PQRS)$. $X$ is not in BCNF. Suppose $X$ is decomposed into two schemas $Y$ and $Z$, where $Y=(PR)$ and $Z=(QRS)$ ... $Y$ and $Z$ is dependency preserving and lossless Which of the above statements is/are correct? Both I and II I only II only Neither I nor II
0 votes
0 answers 13 views
The following functional dependencies are given: $AB\rightarrow CD,AF\rightarrow D,DE\rightarrow F,$C\rightarrow G,F\rightarrow E,G\rightarrow A $Which one of the following options is false?$ \left \{ CF \right \}^{*}=\left \{ ACDEFG \right \} \left \{ BG \right \}^{*}=\left \{ ABCDG ... $\left \{ AB \right \}^{*}=\left \{ ABCDG \right \}$
0 votes
0 answers 5 views
Relation $R$ has eight attributes $\text{ABCDEFGH}$. Fields of $R$ contain only atomic values. $F$ = $\text{{CH$\rightarrow$G, A$\rightarrow$BC, B$\rightarrow$CFH, E$\rightarrow$A, F$\rightarrow$EG}}$ is a set of functional dependencies $(FDs)$ so that $F^+$ is exactly the ... in $1NF$, but not in $2NF$. in $2NF$, but not in $3NF$. in $3NF$, but not in $\text{BCNF}$. in $\text{BCNF}$.
0 votes
0 answers 5 views
Consider a schema $R(A,B,C,D)$ and functional dependencies $A \rightarrow B$ and $C \rightarrow D$. Then the decomposition of R into $R_1 (A,B)$ and $R_2(C,D)$ is dependency preserving and lossless join lossless join but not dependency preserving dependency preserving but not lossless join not dependency preserving and not lossless join
0 votes
0 answers 8 views
Which of the following is NOT a superkey in a relational schema with attributes $V,W,X,Y,Z$ and primary key $V\;Y$? $VXYZ$ $VWXZ$ $VWXY$ $VWXYZ$
1 vote
1 answer 18 views
Consider a relation scheme $R = (A, B, C, D, E, H)$ on which the following functional dependencies hold: {$A \rightarrow B$, $BC \rightarrow D$, $E \rightarrow C$, $D \rightarrow A$}. What are the candidate keys R? $AE, BE$ $AE, BE, DE$ $AEH, BEH, BCH$ $AEH, BEH, DEH$
1 vote
1 answer 8 views
A table has fields $Fl, F2, F3, F4, F5$ with the following functional dependencies $F1 → F3$ $F2→ F4$ $(F1 . F2) → F5$ In terms of Normalization, this table is in $1NF$ $2NF$ $3NF$ None of these