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
Correct Answer :
D. None of these
Related Questions
In this data model each record can hae more than one parent
Hierarchical model
E-R model
Network based model
none of these
In RDBMS, Data is presented as a collection of
Relation
Table
Attribute
Entity
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
Encoding method which does not provide for synchronization
B8ZS
Manchester
RZ
NRZ-L
Full form of CIDR
Classful Inter Domain Routing
Classless International Domain Routing
Classless Inter Domain Routing
none of these
The left outer join takes all tuples
in the left relation which didnt match with any tuple in right relation
in the left relation which matched with a tuple in right relation
in the right relation which didnt match with any tuple in left relation
in the right relation which matched with a tuple in left relation
What does the number of attributes in a relation is called?
Cardinality
Degree
Tuple
Order
Select the correct
i) A timestamp-based scheduler cant produce live lock
ii) Aggregate functions cant appear with HAVING clause.
iii) Isolation is a property of database transaction.
i and ii only
ii and iii only
i and iii only
i only
Select the incorrect statement
BCNF is stronger than 3NF
Relational algebra is a non-procedural language
Every conflict serializable schedule is view serializable.
none of the above
Which one of the following statements is false?
The data dictionary is normally maintained by the database administrator.
Data elements in the database can be modified by changing the data dictionary.
The data dictionary contains the name and description of each data element.
The data dictionary is a tool used exclusively by the database administrator.
Referential integrity
controls relationships between operations of an object
controls relationships between instances of a class
controls relationships between attributes in a table
controls relationships between tables in a database
Disk storage is referred to as
sequential access storage
direct access storage
random access storage
none of the above
Object based data models are used in describing the abstraction of the following levels?
Conceptual and view
Only physical
Physical and conceptual
Only conceptual
A subschema expresses
the logical view.
the physical view.
the external view.
all of the above.
The mode in which data item may be locked
Partner
Mutual
Exclusive
Atomic
Which of the following layer uses trailer of the frame for error detection?
Transport layer
Network layer
Datalink layer
None of these
Which of the following extracts its data from the result of an SQL SELECT statement.
View
Synonym
Sequence
Transaction
In mesh topology, if the number of devices is n , then the number of ports present in each device is
n
n+1
n-1
n/2
Which one of the following is provided by a data dictionary ?
User data
Database structure data
Sorted data
Functional data
Data stored in cursor is called ……………
record
active data set
object
none of the above
In two-phase locking
the data items are locked in growing phase.
the data items are released in shrinking phase.
Both A and B are true
Both A and B are false
Select the correct statement
i) Aggregate functions work on a group of data and return a single value.
ii) ODBC connects the frontend with the database without considering its compatibility
iii) View definition cant be used at multiple places through with clause .
i and ii only
ii and iii only
i and iii only
i only
A transaction is said to have terminated if it has
either committed or aborted
either partially committed or aborted
either committed or failed
none of these
The access protocol used by traditional Ethernet
CSMA/CA
CSMA/CD
CSMA
Token ring
Specialization is a
top-down approach.
bottom-up approach.
left-right approach.
none of the above
In the architecture of a database system external level is the
physical level.
logical level.
conceptual level
view level.
Which of the following operator preserves unmatched rows of the relations being joined?
Inner join
Outer join
union
Intersect
The output of the Data Definition Language is stored in the
view table
schema
metadata
all of the above.
In an Entity-Relationship Diagram Diamonds represents
Attributes
Multi-valued attributes
Weak entity set
Relationship sets
Which of the following is a classical approach to database design?
Left Right approach
Right Left approach
Top Down approach
Bottom Up approach