_____ command can be used to modify a column in a table
alter
update
set
create
Correct Answer :
A. alter
Related Questions
The concept of mapping of ______ entity types is the concept in which the for each strong entity type E in the ER schema, create a relation R that includes all the simple attributes of E.
Regular
Irregular
None
Weak
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.
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
A _____ is used to define overall design of the database
code
data definition language
application program
schema
Wait-for graph is used for
detecting view serializability.
detecting conflict serializability.
deadlock prevention
deadlock detection
In 2NF
No functional dependencies (FDs) exist.
No multivalued dependencies (MVDs) exist.
No partial FDs exist.
No partial MVDs exist.
Relations produced from an E-R model will always be
First normal form.
Second normal form.
Third normal form.
Fourth normal form.
A top-to-bottom relationship among the items in a database is established by a
Hierarchical schema
Network schema
Relational Schema
All of the above
______contains information that defines valid values that are stored in a column or data type.
Default
Index
Rule
View
DBMS helps achieve
Centralized control of data
Data independence
Both A and B
Neither A nor B
In an E-R, Y is the dominant entity and X is a subordinate entity. Then which of the following is incorrect :
Operationally, if Y is deleted, so is X
existence is dependent on Y.
Operationally, if X is deleted, so is Y.
Operationally, if X is deleted, & remains the same.
Which of the following addressing modes permits relocation without any change over in the code?
Indirect addressing
Indexed addressing
PC relative addressing
Base register addressing
As per equivalence rules for query transformation, selection operation distributes over
Union.
Set difference.
Intersection.
All of the above.
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
Which of the following is not a recovery technique?
Deferred update
Immediate update
Two-phase commit
Shadow paging
Checkpoints are a part of
Recovery measures.
Security measures.
Concurrency measures.
uthorization measures.
In an ER model,_____ is described in the database by storing its data.
Entity
Attribute
Relationship
Notation
The common column is eliminated in
theta join
outer join
natural join
composed join
_______ product was acquired by Informix, integrated into its RDBMS and introduced as the Informix Universal Server an ORDBMS.
Star
llustar
SQL
Cygnus
The data in the database at a particular moment of time is called the _______
Snapshot
Dynaset
Stateless
Stateful
If a transaction T has obtained an exclusive lock on item Q, then T can
read Q
write Q
both read and write Q
write Q but not read Q
The clause in SQL that specifies that the query result should be sorted in ascending or descending order based on the values of one or more columns is
View
Order by
Group by
Having
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
______ 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
Which of the following is a reason to model data?
Understand each user's perspective of data
Understand the data itself irrespective of the physical representation
Understand the use of data across application areas
All of the above
_____is a full form of SQL.
Standard query language
Sequential query language
Structured query language
Server side query language
______is a preferred method for enforcing data integrity
Constraints
Triggers
Stored procedure
Cursors
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
The _______ is a set of programs to use and / or modify this data.
DBMS
System
Program
Software