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CONCEPT OF DBMS
Edumate Questions
1. Give an example of
RDBMS package
Ans: Oracle, SQL Server,MS
Access,Foxpro, Dbase etc2. Select the property which
is desirable for a database
(a) Redundancy (b)
Inconsistency
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Integrity (d) Complexity
Ans: Integrity
Redundancy means
duplication of same data in
different places of the
database.
Inconsistency:
Redundancy may cause
inconsistency.
3. Pick the odd man out
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(a) Create(b) Select (c)
Update (d) Insert
Ans: Create. It is a DDL
command. All others are
DML commands
4. Name the key that acts as a
candidate key but not a
primary key
Ans: Alternate key
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5. ..is the ability to
modify a scheme definition in
ijne level without affecting
the scheme definition in the
next higher level
Ans: Data Independence
6. For accessing data from a
database
provides an interface with
programming languages
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Ans: SQL or DML
7. Consider the table with the
following fields Name, Roll
Number and Mark for a set of
students. A field among
them, which is suitable for
primary key, Justify answer
Ans: Roll Number
Roll Number can be used to
identify a student uniquely.
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Roll No cannot be repeated
ie. No two students have
same Roll Number
8. For catering to the need of
users, a database is
implemented through three
general levels. Name the
three levels and discuss them
Ans: The three levels are
1. Physical Level
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Physical level describes
how the data stored in storage
medium. This is the
lowest level. At this level
records will be stored in an
actual storage location
2. Logical Level
This level describes what
data are stored in the
database. It describes the
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relationship exist among
data. Here records are
defined, the type of data is
determined, relationships
are specified
3. View Level
This is the highest level. It
is closest to users, this level
concerned with the way
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in which the users view the
data
9. You have to present a
seminar on the topic Keys in
RDBMS prepare a seminar
report
View Level
Logical Level
Physical Level
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Ans: Keys are used to
identify the tuples in a
relation. The important keys
are
1) Primary key: Primary key
is a set of one or more
attributes used to identify a
tuple uniquely in a
relation. Primary key can
not be repeated
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Eg: Reg No. in student
relation
2) Candidate key: Keys that
can act as a primary key is
called candidate key. They
are the candidate key. It is
used to identify a tuple
uniquely
Eg: SI. No., Adm. No. etc
in student relation
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3) Super key: A
combination of primary
key with any other
attribute or group of
attribute is called super key
Eg: Reg. No. + Name in
student relation
4) Foreign key: When a
primary key of one
relationis also available as
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an attribute in aother
relation, that attribute is
called foreign key of the
relation. Foreign key helps
to attain data integrity
5) Alternate key: A
candidate key that is not a
primary key is known as
alternate key
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10. There are different data
models of which one is
currently used in all business
transaction. Specify it and
discuss details
OR
Remesh doing relational
operation in which he used
different tables for
manipulation.
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Which data model he is
using? Discuss in detail
Ans: Relational Data Model
Relational data model uses
a collection of tables to
represent data and its
relationship.
Important features are:
Represent data in form of
rows and column
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Rows represents records
and column represents
attributes or fields
A row is known as tuple
and column is known as
attributes
A relation can be
represented using a named
tableIt is developed by J.F. Code
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Eg. N
ame
Reg
No.
Mark
Ra
him
R
oy
Jo
sy
138
0
138
1
132
48
55
58
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11. Consider the following
table and write the relational
algebra operations for the
following.
DEPOSIT
Acc
No
Name Branch Amoun
100
1
100
2
Kumar
Salim
Fida
John
Calicut
Trivandru
m
Kottayam
10,000
25,000
18,000
30,000
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100
3
100
4
100
5
Raju Kannur
Thrissur
5,000
(a) To display those tuples
fr
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om DEPOSIT relation
where amount is greater
than
25,000
(b) To display only Acc No.
and amount of all
depositors
Ans: (a) s amount> 25,000
(DEPOSIT)
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(b) Acc No, Amount
(DEPOSIT)
12.
STUDENT
GRADE
Reg
No
Name Scores
101
102
103
104
105
Preethi
Anupama
Ruksana
Nancy
Anu
70
68
94
87
77
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Consider the relations
STUDENT and Grade
given above and predictthe output of the following
Reg
No
Scores Grade
101
102
103
104
105
70
68
94
87
77
B+
B
A+
A
B+
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2.Reg No Scores
101
102
103
104
105
70
68
94
87
77
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3.
4.
Reg No Score Grade101
105
70
77
B+
B+
Reg No Name103
104
105
Ruksana
Nancy
Anu
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5.
13. Consider the following
Relations
Reg No Scores Grade101
102
70
68
B+
B
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R1 R2
Reg No Name Grade
1200
1201
1202
Babu
Lulu
Sunu
A
A+
B
Reg No Name Grad
1203
1201
Biju
Lulu
D
A+
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Show the output of the
following relational
operations
(a)R1-R2 (b) R1 R2
(c) R1 R2
Ans: (a) R1-R2
Reg No Name Grade1200
1202
Babu
Sunu
A
B
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(b) R1 R2
(c) R1 R2
Reg No Name Grade1200
1201
1202
1203
Babu
Lulu
Sunu
Biju
A
A+
B
D
Reg No Name Grade1201 Lulu A+
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Data which is composed
off more than one single
valued data is known as multi
valued attribute eg. Date
of birth
15. Consider the following
table and write relational
algebra operations for the
following
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DEPOSIT
Acc
No
Name Branch Amoun
100
1
100
2
Kumar
Salim
Fida
John
Calicut
Trivandru
m
Kottayam
10,000
25,000
18,000
30,000
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100
3
100
4
100
5
Raju Kannur
Thrissur
5,000
(a) To display those tables
from DEPOSIT relation
where amount is greater than
25,000
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(b) To display only Acc
No. and amount of all
deposits
Ans:
(a) s Amount> 25,000
(DEPOSIT)
(b) Acc No, Amount (DEPOSIT)
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