# Recent questions tagged database-normalization

1 vote
1
For a database relation $R(a,b,c,d)$ where the domains of $a,b,c$ and $d$ include only atomic values, only the following functional dependencies and those that can be inferred from them hold. $a \rightarrow c$ $b \rightarrow d$ The relation is in First normal form but not in second normal form Second normal form but not in third normal form Third normal form None of the above
1 vote
2
Let $R=(A,B,C,D,E,F)$ be a relation scheme with the following dependencies: $C\to F,E\to a,EC\to D, A\to B$. Which of the following is a key for $R$? $CD$ $EC$ $AE$ $AC$
3
For a database relation $R(a,b,c,d)$ where the domains of $a,b,c,d$ include only atomic values, only the following functional dependencies and those that can be inferred from them hold: $a\to c\\b\to d$ the relation is in first normal form but not in second normal form. second normal form but not in third normal form. third normal form. none of these.
4
Normalization from which is based on transitive dependency is classified as: First normal form. Second normal form. Fourth normal form. Third normal form.
5
In functional dependency between two sets of attribute $A$ and $B$ then set of attributes $A$ of database is classified as: top right side down left side left hand side right hand side
6
Which one of the following statements about normal forms is FALSE? BCNF is stricter than $3$NF. Lossless, dependency-preserving decomposition into BCNF is always possible. Lossless, dependency-preserving decomposition into $3$NF is always possible. Any relation with two attributes is BCNF.
7
If attribute of relation schema $R$ is member of some candidate key then this type of attributes are classified as: atomic attribute candidate attribute non-prime attribute prime attribute
8
Process of analyzing relation schemas to achieve minimal redundancy and insertion or update anomalies is classified as: normalization of data. denomination of data. isolation of data. de-normalization of data.
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Rule which states that addition of same attributes to right side and left side will result in other valid dependency is classified as referential rule inferential rule augmentation rule reflexive rule
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If every functional dependency in set $E$ is also in closure of $F$ then this is classified as $FD$ is covered by $E$ $E$ is covered by $F$ $F$ is covered by $E$ $F$ plus is covered by $E$
11
Considering relational database, functional dependency between two attributes $A$ and $B$ is denoted by $A\to B$ $B\gets A$ $AB\to R$ $R\gets AB$
12
Which one of the following statements are not correct? $S1$: $3$NF decomposition is always lossless join and dependency preserving. $S2$: $3$NF decomposition is always lossless join but may or may not be dependency preserving. $S3$: BCNF decomposition is always lossless join and dependency ... but may or may not be dependency preserving. Only $S1$ Only $S4$ Both $S1$ and $S4$ Both $S2$ and $S3$
1 vote
13
Which of the following is TRUE? Every relation in $3$NF is also in BCNF A relation R is in $3$NF if every non-prime attribute of R is fully functionally dependent on every key of R Every relation in BCNF is also in $3$NF No relation can be in both BCNF and $3$NF.
14
Consider the relational schema $R(A B C D)$ with following $FD$ set $F=\{A \to CE, B \to D, AE \to D\}$. Identify the highest normal form satisfied by the relation $R$. $2$NF BCNF $3$NF $1$NF
15
Consider the relational schema $\text{R(A B C D)}$ with following functional dependency set $F=\{A\rightarrow BC,C\rightarrow D\};$ The relation $\text{R}$ is in $2$NF BCNF $3$NF $1$NF
16
Which one is correct w.r.t. RDBMS? primary key $\subseteq$ super key $\subseteq$ candidate key primary key $\subseteq$ candidate key $\subseteq$ super key super key $\subseteq$ candidate key $\subseteq$ primary key super key $\subseteq$ primary key $\subseteq$ candidate key
17
For database relation $R(A,B,C,D)$ where the domains of $A,B,C$ and $D$ include only atomic values, only the following functional dependencies and those that can be inferred from them are: $A \rightarrow C$ $B \rightarrow D$ The relation $R$ is in First ... well as in second normal form Second normal form but not in third normal form. Both in second normal form as well as in third normal form.
18
If every non-key attribute functionally dependent on the primary key, then the relation will be in First normal form Second normal form Third normal form Fourth Normal form
19
The multivalued dependencies (MVDs) can be eliminated using ______ normal form on _____ normal form relations. $1$st, $2$nd $2$nd, $3$rd $3$rd, BCNF $4$th, BCNF
20
In relational databases, if relation R is in BCNF, then which of the following is true about relation R? R is in 4NF R is not in 1NF R is in 2NF and not in 3NF R is in 2NF and 3NF
21
In a relation, if every attribute is prime but key may not be simple then the relation is in ______. A. 1NF B. 2NF C. 3NF D. BCNF
1 vote
22
Consider the relation $R\left ( A,B,C,D,E \right )$ with functional dependencies $F=${ $A\rightarrow B$ $BC\rightarrow E$ $ED\rightarrow A$ } Number of additional relation required to convert it into lossless , dependency preserving $3NF$ decomposition is _____________ What is meaning of additional relation (Here no table mentioned previously)??
23
Consider the following relational schemes: R(A, B, C, D, E, F) and S(A, B, C) with in the following functional dependencies: I. AB --> C II. C --> ABDE III. ADE --> F Assume {A,B} is the key for both schemes. Which of the following statements is true? R ... : only AB→ C is the relation for the S table, which satisfies BCNF properties. (So S is in BCNF) Please let me know if it is correct or not.
24
Consider a relation $R\left ( A,B,C,D,E \right )$ and functional dependencies are $F=\left \{ AC\rightarrow B,C\rightarrow D,A\rightarrow E,C\rightarrow B \right \}$ Relation $R$ is decomposed into $R_{1}\left ( A,B,C \right )$ and $R_{2}\left ( C,D \right )$ Then Is it a lossless decomposition? I am getting doubt, how it can be not lossless decomposition?
25
Decompose into BCNF R(A, B, C, D, E) FD: AB->C, C->D, D>B, D->E
1 vote
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Do we need to find closure of functional dependencies of original relation to check whether the decomposed tables are in 2NF . I know that we have to do the above process for 3NF and BCNF . If yes , please give a example where we need to do it