Key to represent relationship between tables is called
primary key
secondary key
foreign key
none of the above
Correct Answer :
C. foreign key
Related Questions
What is a disjoint less constraint?
It requires that an entity belongs to no more than one level entity set.
The same entity may belong to more than one level.
The database must contain an unmatched foreign key value.
An entity can be joined with another entity in the same level entity set.
The part of a database management system which ensures that the data remains in a consistent state is
authorization and integrity manager
buffer manager
transaction manager
file manager
If two relations R and S are joined, then the non matching tuples of both R and S are ignored in
left outer join
right outer join
full outer join
inner join
The relational model is based on the concept that data is organized and stored in two-dimensional tables called ______
Fields
Records
Relations
Keys
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
If the closure of an attribute set is the entire relation then the attribute set is a
superkey
candidate key
primary key
not a key
In 2NF
No functional dependencies (FDs) exist.
No multivalued dependencies (MVDs) exist.
No partial FDs exist.
No partial MVDs exist.
The statement that is executed automatically by the system as a side effect of the modification of the database is
backup
assertion
recovery
trigger
Key to represent relationship between tables is called
primary key
secondary key
foreign key
none of the above
_____ First proposed the process of normalization.
Edgar. W
Edward Stephen
Edgar F. Codd
Edward Codd
Which of the following aggregate functions does not ignore nulls in its results?.
COUNT .
COUNT (*)
MAX
MIN
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.
The fact that all employees of a particular organization should not have salaries more than $10000 is a _____ constraint.
Schema
Tuple
Domain
Relational
____ table store information about database or about the system.
SQL
System
Nested
None of these
______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
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
If both the functional dependencies : X�Y and Y�X hold for two attributes X and Y then the relationship between X and Y is
M:N
M:1
1:M
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
Cascading rollback is avoided in all protocol except
strict two-phase locking protocol.
tree locking protocol
two-phase locking protocol
validation based protocol.
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
It is an abstraction through which relationships are treated as higher level entities
Generalization.
Specialization.
Aggregation.
Inheritance.
The set of all values that can be taken by the attribute is called as _______ of the attribute.
Tuple
Cardinality
Degree
Domain
The clause alter table in SQL can be used to
add an attribute
delete an attribute
alter the default values of an attribute
all of the above
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 relation is in attribute of other composite key. if an attribute of a composite key is dependent on an
2NF
3NF
BCNF
1NF
In an E-R diagram double lines indicate
Total participation.
Multiple participation.
Cardinality N.
None of the above.
In E-R Diagram total participation is represented by
Double lines
Single line
Dashed lines
Triangle
Create a table with the following attributes: Employee(EMPNO integer, EMPNAME of 10 characters)
Create table Employee(EMPNO int, EMPNAME char(10));
Create table Employee(EMPNO integer, EMPNAME String(10));
Create table Emplo(EMPNO number, EMPNAME string);
Create table Emp(EMPNO int, EMPNAME char(10));
Which of the following relational algebraic operations is not from set theory?
Union
Intersection
Cartesian Product
Select
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