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Recent questions tagged database-normalization

2 votes
4 answers
1
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 $S3$
asked Mar 30 in Databases Lakshman Patel RJIT 208 views
1 vote
2 answers
2
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.
asked Mar 30 in Databases Lakshman Patel RJIT 63 views
0 votes
3 answers
3
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
asked Mar 30 in Databases Lakshman Patel RJIT 116 views
0 votes
3 answers
4
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
asked Mar 30 in Databases Lakshman Patel RJIT 178 views
0 votes
5 answers
5
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
asked Mar 24 in Databases jothee 121 views
0 votes
3 answers
6
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.
asked Mar 24 in Databases jothee 135 views
4 votes
13 answers
7
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
asked Jan 13 in Databases Satbir 1.4k views
0 votes
1 answer
8
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
asked Aug 4, 2019 in Others gatecse 80 views
3 votes
5 answers
9
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
asked Jul 2, 2019 in Databases Arjun 757 views
2 votes
4 answers
10
1 vote
2 answers
11
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)??
asked May 19, 2019 in Databases srestha 341 views
0 votes
1 answer
12
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.
asked May 10, 2019 in Databases pritam946 177 views
4 votes
4 answers
13
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?
asked Apr 28, 2019 in Databases srestha 269 views
0 votes
2 answers
14
0 votes
1 answer
16
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
asked Mar 30, 2019 in Databases ashunimbz 73 views
0 votes
1 answer
17
Consider 2 tables R1 and R2 . If we perform a cross product between them the condition that should be satisfied for not generating spurious tuples is both should have a common element which should be a 1>primary key 2>candidate key 3>super key In one of the tables which of the three is correct??
asked Mar 19, 2019 in Databases Doraemon 65 views
0 votes
2 answers
18
Consider a relation $R (A, B, C, D, E, F, G, H) $ where each attribute is atomic, and following functional dependencies exist. Following relation is in $1 NF, $ I help me to decompose relation into $BCNF$ $CH\rightarrow G$ $A\rightarrow BC$ $B\rightarrow CFH$ $E \rightarrow A$ $F\rightarrow EG$
asked Feb 11, 2019 in Databases anusuccess 342 views
8 votes
1 answer
19
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
asked Feb 7, 2019 in Databases Arjun 3.4k views
2 votes
2 answers
20
S: If a relation R is in 3NF but not in BCNF then relation R must consist atleast 2 overlapped candidate keys. True/False
asked Jan 28, 2019 in Databases Reshu $ingh 379 views
0 votes
1 answer
21
Find the highest normal form. AB - - > CE E - - >AB C-->D Doubt AB, E are the candidate key. The answer given is 2NF In 2NF, there should be no partial dependency which is PRIME ATTRIBUTE - - >NON PRIME ATTRIBUTE But it is there in AB-->CE, I think CE is non prime attribute. Or bcoz of E we consider them as prime attribute.
asked Jan 25, 2019 in Databases Jyoti Kumari97 152 views
0 votes
1 answer
23
Select the ‘False’ statement from the following statements about Normal Forms: 1. BCNF is stronger than 3NF 2. Lossless preserving decomposition into BCNF is always possible 3. ​​​​​​​ Any Relation with two attributes is in BCNF 4. Lossless preserving decomposition into 3NF is always possible
asked Jan 21, 2019 in Databases Hardik Vagadia 137 views
0 votes
0 answers
25
Are 3NF decompostions and BCNF decompostions unique? Are 4NF important for GATE (since I've left them :( ) See, I am asking this question because I want to know whether they'll ask about no. of tables we get after normalizing upto 3nf or bcnf. Now, if the decompostions are ... question or not I am in a bit hurry to search for that.. so please forgive me if it has been already asked.) Thank you.
asked Jan 21, 2019 in Databases Harsh Kumar 74 views
0 votes
1 answer
26
Consider the schema R = (S T U V) and the dependencies S → T, T → U, U → V and V → S. Let R = (R1 and R2) be a decomposition such that R1 ∩ R2 = ϕ. (In the actual gate question it was R1∩R2 ≠ ϕ) The decomposition is:- not in 2NF in 2NF but not 3NF in 3NF but not in 2NF in both 2NF and 3NF
asked Jan 21, 2019 in Databases Sukhbir Singh 170 views
0 votes
0 answers
28
Business Rules : An employee may work in many departments. Each employee has a unique employee number. Each departments has many managers. An employee has only one manager for each department Each manager can manage only one department. Each employee has only one Name. The given ... . HOW? NOTE : according to the solution eid should be the primary key. BUT how can you find manager with only eid?
asked Jan 17, 2019 in Databases OneZero 50 views
0 votes
1 answer
29
0 votes
0 answers
30
Can someone explain the paragraph marked based on relation $r$ given in Figure 7.2? Reference: Database System Concepts by Silberschatz, Korth, Sudarshan 4th Edition. ​​​​​
asked Jan 5, 2019 in Databases zeeshanmohnavi 67 views
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