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Use of DDL
I am currently studying database . In the Raghu Rmakhrishnan it has been written that "the DDL languages is used in both external level and Conceptual level ". Please el...
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3 3 votes
1 1 answer
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relational calculus
BOOK(ACC_NO, TITLE, YR_PUB)USER(CARD_NO, B_NAME, B_ADD)B_BY(ACC_NO , CARD_NO , DOI)SUPPLIER(S_NAME,S_ADD)S_BY(S_NAME,S_NAME,PRICE,,DOS)Query :- find the names of those su...
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1.1k
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why XY-> X is always functionally dependent(trivial )
for attribute set D the functional dependency D->D is considerd as trival i.e. D functionally determines itself.but how for D={a,b,c,d,e}i can have relation R which i...
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1 1 answer
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Navathe-Fundamentals of Database systems-basic SQL-sixth edition-4.12
Specify the following queries in SQL on the database schema of Figure 1.2.Figure 1.2:A database that storesstudent and courseinformation.CaptionRetrieve the names of all ...
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11 11 votes
5 answers 5 answers
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To calculate how many no of super keys?
a relation R(A,B,C,D,E,F,G,H)and set of functional dependencies are {CH->G,A->BC,B->CFH,E->A,F->EG }then how many possible super keys are present ?
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Navathe-Fundamentals of Database systems-basic SQL-sixth edition-4.10
Specify the following queries in SQL on the COMPANY relational database schema shown in figure 3.5 .Show the result of each query if it is applied to the COMPANY databas...
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1 1 vote
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Navathe-Fundamentals of Database systems-basic SQL-sixth edition-4.11
Specify the updates of Exercise 3.11 using the SQL update commands.EXERCISE 3.11 : Suppose that each of the following Update operations is applied directly to the databa...
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737
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Navathe-Fundamentals of Database systems-basic SQL-sixth edition-4.14
Design a relational database schema for a database application of your choice.Declare your relations,using the SQL DDL.Specify a number of queries in SQL that are needed ...
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3 3 votes
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Navathe-Fundamentals of Database systems-basic SQL-sixth edition-4.8
Write appropriate SQL DDL statements for declaring the LIBRARY relational database schema of figure below. Specify the keys and referential triggered actions.
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686
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Navathe-Fundamentals of Database systems-basic SQL-sixth edition-4.2
List the data types that are allowed for SQL attributes.
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Navathe-Fundamentals of Database systems-basic SQL-sixth edition-4.7
Consider the LIBRARY relational database schema shown in the figure below .Choose the appropriate action (reject, cascade, set to NULL, set to default) for each referenti...
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768
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Navathe-sixth edition-4.5
Consider the database shown below ,Whose schema is also shown below .What are the referential integrity constraints that should hold on the schema ? Write appropriate $SQ...
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4 4 answers
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What will COUNT(*) returns if all the collection has only null values?
What will COUNT(*) returns if all the collection has only null values???
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3 3 votes
2 2 answers
3.1k
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maximum no of tuples
Consider the relation R1( P, Q, R, S ) and R2 ( R, G, T, U )The relation R1 has 20 tuples and R2 has 10 tuples then maximum number of tuples in R1 ⟕ R2 is ...........
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8 8 votes
1 1 answer
1.9k
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maximum no of touples
Consider the following relation:R (A B C) A primary key with 100 tuples.S (E F G) E primary key with 50 tuples.T (AE D) AE primary key with 80 tuples.U (D G H) H primary ...
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99 99 votes
11 answers 11 answers
37.3k
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GATE CSE 2016 | Set 1 | Question: 51
Consider the following two phase locking protocol. Suppose a transaction $T$ accesses (for read or write operations), a certain set of objects $\{O_1,\ldots,O_k \}$. This...
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105 105 votes
8 answers 8 answers
30.0k
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GATE CSE 2016 | Set 1 | Question: 23
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...
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32 32 votes
3 answers 3 answers
12.4k
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GATE CSE 2016 | Set 1 | Question: 22
Which one of the following is NOT a part of the ACID properties of database transactions?AtomicityConsistencyIsolationDeadlock-freedom
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52 52 votes
3 answers 3 answers
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GATE CSE 2016 | Set 1 | Question: 21
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$$VWXYZ$
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82 82 votes
3 answers 3 answers
18.6k
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GATE CSE 2016 | Set 2 | Question: 52
Consider the following database table named water_schemes:$$\overset{\text{Water_schemes}}{\begin{array}{|c|c|c|}\hline\textbf{scheme_no}& \textbf{district_name}& \te...
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106 106 votes
12 answers 12 answers
37.1k
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GATE CSE 2016 | Set 2 | Question: 51
Consider the following database schedule with two transactions $T_{1}$ and $T_{2}$.$S= r_{2}\left(X\right); r_{1}\left(X\right); r_{2} \left(Y\right); w_{1} \left(X\right...
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63 63 votes
5 answers 5 answers
19.8k
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GATE CSE 2016 | Set 2 | Question: 21
B+ Trees are considered BALANCED because.The lengths of the paths from the root to all leaf nodes are all equal.The lengths of the paths from the root to all leaf nodes d...
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54 54 votes
8 answers 8 answers
26.2k
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GATE CSE 2016 | Set 2 | Question: 22
Suppose a database schedule $S$ involves transactions $T_1,\ldots,T_n$ . Construct the precedence graph of $S$ with vertices representing the transactions and edges repr...
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1 1 vote
2 2 answers
3.5k
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dbms
Consider the relation $R(X Y Z)$ has the following tuples XYZ123124321_________ tuples in the result of following relational algebra expression$(\underset{X,Y}...
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6 6 votes
1 answers 1 answer
5.2k
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MadeEasy Test Series: Databases - B Tree
What is the minimum levels of B+ tree index required for 5000 keys and order of B+ tree node (P) is 10. (Assume P is the max pointer possible to store in B+ tree node) My...
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0 0 votes
1 1 answer
799
799 views
FOERIGN KEY
what is the advantage of keeping the Foreign Key null as we know if we make the Foreign Key null we cant reference it again so thats a disadvantage ......so there must be...
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0 0 votes
2 2 answers
1.3k
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View serializable
S: T1(A)R2(B)W2(B)R2(A)W2(B)W1(A)R3(B)W3(B) Given schedule is view serializable ?
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0 0 votes
1 answers 1 answer
768
768 views
From where should I study view serializability?
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2 2 votes
1 answers 1 answer
998
998 views
transactions
scheduleR(A) R(B) R(B) W(A) COMMIT R(C) R(B) W(C) W(B) R(A) R(C) COMMIT COMMITThe above scedule is -:a)conflict serializableb)recoverablec)cascadelessd)all ...
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0 0 votes
1 1 answer
637
637 views
Virtual Gate Test Series: Databases - Query Interpretation
The inner query in Q1 will select the employee having max salary from all other employees in all departments(this will return the max salaried employee in the entire comp...
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