In SQL, testing whether a subquery is empty is done using
DISTINCT
UNIQUE
NULL
EXISTS
Correct Answer :
D. EXISTS
Related Questions
Protection of data from unauthorized Disclosure results in loss of _______
Integrity
Availability
Confidentiality
Discretionary Security
______contains information that defines valid values that are stored in a column or data type.
Default
Index
Rule
View
In b-tree the number of keys in each node is than the number of its children.
one less
same
one more
half
The transactions like adding an employee, enrolling a student in a course are examples of _______
Logical
Physical
None
Theoretical
______ keyword is used to find the number of values in a column.
TOTAL
ADD
COUNT
SUM
The normal form that is not necessarily dependency preserving is
2NF
3NF
BCNF
4NF
The fact that information in the data warehouse changes far less often and may be regarded as non-real-time with periodic updating; This implies that data warehouses are _______
Volatile
Non - Volatile
Logical
Physical
The full form of GUI is _________
Government Union Internet
Graphical Unit Interface
Graphical User Interface
Graphical University Interface
The relational model is based on the concept that data is organized and stored in two-dimensional tables called ______
Fields
Records
Relations
Keys
Grant and revoke are _____ statements.
TCL
DCL
DDL
DML
Wait-for graph is used for
detecting view serializability.
detecting conflict serializability.
deadlock prevention
deadlock detection
Relations produced from an E-R model will always be
First normal form.
Second normal form.
Third normal form.
Fourth normal form.
______is a special type of integrity constraint that relates two relations & maintains consistency across the relations.
Domain Integrity Constraints
Referential Integrity Constraints
Domain Constraints
Entity Integrity Constraints
Manager salary details are hidden from the employee .This is
Conceptual level data hiding.
External level data hiding.
Physical level data hiding.
None of these.
Which two files are used during operation of the DBMS?
Query languages and utilities
DML and query language
Data dictionary and transaction log
Data dictionary and query language
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
_______ product was acquired by Informix, integrated into its RDBMS and introduced as the Informix Universal Server an ORDBMS.
Star
llustar
SQL
Cygnus
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
The rule that a value of a foreign key must appear as a value of some specific table is called a
Referential constraint.
Index.
Integrity constraint.
Functional dependency.
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
Relationships among relationships can be represented in an-E-R model using
Aggregation
Association
Weak entity sets
Weak relationship sets
The drawback of shadow paging technique are
Commit overhead
Data fragmentation
Garbage collection
All of these
According to the levels of abstraction, the schema at the intermediate level is called
Logical schema.
Physical schema.
Subschema.
None of the above.
In an E-R diagram double lines indicate
Total participation.
Multiple participation.
Cardinality N.
None of the above.
Which one is correct statement?
Logical data independence provides following without changing application programs:
(i) Changes in access methods.
(ii) Adding new entities in database
(iii) Splitting an existing record into two or more records
(iv) C
(i) and (ii)
(iv) only
(i) and (iv)
(ii) and (iii)
In a relational schema, each tuple is divided into fields called
Relations
Queries
Domains
All of the above
By ______ an area on disk in certain ways, one can make it represent a bit value of either zero (0) or one (1).
Vulcanizing
Galvanizing
Magnetizing
Passing UV rays
Key to represent relationship between tables is called
primary key
secondary key
foreign key
none of the above
The ____ operator joins two or more conditions and displays rows only if that rows data satisfies all conditions specified.
OR
AND
NOT
ALL
______defines the structure of a relation which consists of a fixed set of attribute-domain pairs.
Instance
Program
Schema
Super Key