An advantage of views is
Data security
Derived columns
Hiding of complex queries
All of the above
Correct Answer :
A. Data security
Related Questions
____ table store information about database or about the system.
SQL
System
Nested
None of these
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 keyword to eliminate duplicate rows from the query result in SQL is
DISTINCT
NO DUPLICATE
UNIQUE
None of the above
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
Key to represent relationship between tables is called
primary key
secondary key
foreign key
none of the above
The ______ key of a relation is the attribute (column) or collection of attributes, which uniquely identify a given tuple.
Primary
Foreign
Candidate
Alternate
The ____ operator joins two or more conditions and displays rows only if that rows data satisfies all conditions specified.
OR
AND
NOT
ALL
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.
______contains information that defines valid values that are stored in a column or data type.
Default
Index
Rule
View
A weak entity has an ______ dependency on its owner entity, which can be used for both ON UPDATE and ON DELETE.
Direct
Indirect
Existence
No
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
Employees in a company are each assigned their own office, i.e. for each employee there exists a unique office and for each office there exists a unique employee; This statement is an example of ____ type of relation.
1:1
1: Many
Many: One
Many : Many
The values of the attribute describes a particular
Entity set
File
Entity instance
Organization
The collection of information stored in a database at a particular moment is called as ......
schema
instance of the database
data domain
independence
A _____ is a logical unit of database processing that includes one or more data access operations that can include insertion, deletion, modification or retrieval operations.
Database
Data
Transaction
Record
Which of the following statement on the view concept in SQL is invalid?
All views are not updateable
The views may be referenced in an SQL statement whenever tables are referenced.
The views are instantiated at the time they are referenced and not when they are defined.
The definition of a view should not have GROUP BY clause in it.
The statement that is executed automatically by the system as a side effect of the modification of the database is
backup
assertion
recovery
trigger
In an ER model,_____ is described in the database by storing its data.
Entity
Attribute
Relationship
Notation
The relational model is based on the concept that data is organized and stored in two-dimensional tables called ______
Fields
Records
Relations
Keys
The fact that all employees of a particular organization should not have salaries more than $10000 is a _____ constraint.
Schema
Tuple
Domain
Relational
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)
Immediate database modification technique uses
Both undo and redo.
Undo but no redo.
Redo but no undo.
Neither undo nor redo.
The ______ indexes are forced to store only record IDs in the data structure and require at least one additional I/O Operation to retrieve the actual record.
Clustered
Hashed
Un-clustered
Collision
According to the levels of abstraction, the schema at the intermediate level is called
Logical schema.
Physical schema.
Subschema.
None of the above.
The normal form that is not necessarily dependency preserving is
2NF
3NF
BCNF
4NF
In SQL the statement select * from R, S is equivalent to
Select * from R natural join S.
Select * from R cross join S.
Select * from R union join S.
Select * from R inner join S.
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
Data independence means
data is defined separately and not included in programs.
programs are not dependent on the physical attributes of data
programs are not dependent on the logical attributes of data
both B and C
In an ER diagram the ___shape specifies the Attibute and a ____ shape specifies the primary key attribute.
Oval; An oval with an underlined attribute
Circle; A circle with bolded attribute inside it
Diamond; A bolded attribute
Square; An attribute within the square
In an E-R diagram double lines indicate
Total participation.
Multiple participation.
Cardinality N.
None of the above.