Noiseless channel has ……… types of protocols.
2
3
4
5
Correct Answer :
A. 2
Related Questions
A transaction which may not complete its execution successfully is termed as
Failed
Aborted
Blocked
Finished
A logical description of some portion of database that is required by a user to perform task is called as
System View
User View
Logical View
Data View
The maximum number of children in a B-tree of order m is
m+1
m
m-1
m/2
DBMS helps achieve
Data independence
Centralized control of data
Neither A) nor B)
both A) and B)
The exists construct returns the value true, if the argument subquery is
empty
nonempty
contains null values
none of the above
In a Hierarchical model records are organized as
Graph.
List.
Links.
Tree.
FDDI protocol operates in
i) Transport layer
ii) Network layer
iii) Datalink layer
iv) Physical layer
i and ii only
ii and iii only
i and iii only
iii and iv only
The race condition occurs when
Two concurrent processes attempt to interact with each other.
Two concurrent processes interact with different data files.
Two concurrent processes attempt to hold a data item .
none of the above.
Which of the following file organization provides very fast access to any arbitrary record of a file?
Ordered file
Unordered file
Hashed file
B-tree
B-Tree is used for
searching data
storing data
both A and B
none of these
The syntax to select all column from the table is
select all from tablename
select * from tablename
select from tablename
none of these
In client/server computing data are
sent only upon the client's request
sent in complete copies for the client to filter and sort
never sent to the client machine
sent in very large sections to save processing time
A …………… is a memory area where data are processed.
view
trigger
cursor
none of the above
Which of the following is not an Aggregate function?
Min
Max
Select
Avg
Which of the following will NOT eliminates the ambiguities of a null value?
Define the attribute as required
Define subtypes
Define each attribute as having an initial value that is recognized as blank
Define supertypes
The minimal set of super key is called
Primary key
Secondary key
Candidate key
Foreign key
A subschema expresses
the logical view.
the physical view.
the external view.
all of the above.
A lock that allows concurrent transactions to access different rows of the same table is known as a
Field-level lock
Row-level lock
Table-level lock
Database-level lock
Which of the following statement returns data to the host variables one at a time?
SELECT
RETURN
FETCH
GET
Which of the following normalization is needed, if an attribute of a composite key is dependent on an attribute of the other composite key?
BCNF
Second
Third
Fourth
The ability to modify the conceptual schema without causing any change to the application program is known as
Physical data independence
Logical data independence
External data independence
Static data
In case of entity integrity, the primary key may be
not Null
Null
both Null & not Null.
any value.
Which of the following is true statement ?
SQL permits attribute names to be repeated in the same relation.
a SQL query automatically eliminates duplicates.
a SQL query will not work if there are no indexes on the relations
None of these
The raw facts and figures are:
Data
Data field
DBMS
DBASE
Generalization is a
top-down approach.
bottom-up approach.
left-right approach.
none of the above
Disk storage is referred to as
sequential access storage
direct access storage
random access storage
none of the above
Select the incorrect statement(s)
i) Foreign key values can be left blank
ii) In SQL duplicates may be present
iii) Theta join operation doesnt remove duplicate columns.
iv) NULL value means string of blank characters.
i ,iii only
ii, iv only
iii, iv only
ii, iii, iv
The physical location of a record is determined by a mathematical formula that transforms
a file key into a record location is :
B-Tree File
Hashed File
Indexed File
Sequential file.
............... noise is caused by the random motion of the electrons in a wire and is avoidable.
Thermal
Intermodulation
Cross talk
Impulse
Benefit of database normalization is
smaller number of tables
higher query processing efficiency
reduced I/O for most queries
reduced data redundancy