Which of the following relational algebra operations do not require the participating tables to be union-compatible?
Union
Intersection
Difference
Join
Correct Answer :
D. Join
Related Questions
______contains information that defines valid values that are stored in a column or data type.
Default
Index
Rule
View
A ____ key specifies a uniqueness constraint that no two distinct tuples in any state r of relation R can have the same value for super key.
Sub
Parent
Candidate
Super
What is data integrity?
It is the data contained in database that is non redundant.
It is the data contained in database that is accurate and consistent.
It is the data contained in database that is secured.
It is the data contained in database that is shared.
Which of the following is not comparison operator?
<>
<
=<
>=
______is a preferred method for enforcing data integrity
Constraints
Triggers
Stored procedure
Cursors
Which of the following is not a characteristic of a relational database model?
Table
Tree like structure
Complex logical relationship
Records
The data models defined by ANSI/SPARC architecture are
Conceptual, physical and internal
Conceptual, view and external
Logical, physical and internal
Logical, physical and view
If an entity can belong to only one lower level entity then the constraint is
disjoint
partial
overlapping
single
Which of the following concurrency control schemes is not based on the serializability property?
Two - phase locking
Graph-based locking
Time-stamp based locking
None of these .
In a multi-user database, if two users wish to update the same record at the same time, they are prevented from doing so by
jamming
password
documentation
record lock
A data type or format is specified for each _________
Relation
Tuple
Database
Domain
The cost of reading and writing temporary files while evaluating a query can be reduced by
building indices
pipelining
join ordering
none of the above
A _____ is used to define overall design of the database
code
data definition language
application program
schema
_____is a full form of SQL.
Standard query language
Sequential query language
Structured query language
Server side query language
When an E-R diagram is mapped to tables, the representation is redundant for
weak entity sets
weak relationship sets
strong entity sets
strong relationship sets
The one guideline to be followed while designing the database is
A database design may be ambiguous.
It should avoid/reduce the redundancy.
Unrelated data should be in the same table so that updating the data will be easy.
An entity should not have attributes.
Which of the following constitutes a basic set of operations for manipulating relational data?
Predicate calculus
Relational calculus
Relational algebra
SQL
The ______ language consists of SQL statements for operating on the data (insert, Modify, Delete) in tables that already exist.
Data Manipulation
Data Definition
Data Control
None
A DBMS is a ____ user if at most one user can use the system and is mostly restricted to personal computer systems.
None
Multi
Single
Concurrent
An advantage of the database management approach is
data redundancy increases
data is dependent on programs
data is integrated and can be accessed by multiple programs
none of the above
The language that requires a user to specify the data to be retrieved without specifying exactly how to get it is
Procedural DML.
Non-Procedural DML.
Procedural DDL.
Non-Procedural DDL.
The ____ operator joins two or more conditions and displays rows only if that rows data satisfies all conditions specified.
OR
AND
NOT
ALL
Consider the join of relation R with a relation S. If R has m tuples and S has n tuples, then the maximum and minimum size of the join respectively are
m+n and 0
m+n and |m-n|
mn and 0
mn and m+n
Which of the following is not a property of transactions?
Atomicity
Concurrency
Isolation
Durability
The size of a data item is called its _______, which can be a field of some record or may be a larger unit such as a record.
Similarity
Granularity
Dimensionality
Arity
Wait-for graph is used for
detecting view serializability.
detecting conflict serializability.
deadlock prevention
deadlock detection
Shadow paging has
no redo
no undo
redo but no undo
neither redo nor undo
The _____ category includes storage media that can be operated on directly by the computers central processing unit.
Primary storage
Secondary Storage
All
Tertiary Storage
Which of the following is not a logical database structure?
Chain
Network
Tree
Relational
Isolation of the transactions is ensured by
Transaction management
Application programmer
Concurrency control
Recovery management