|
|
Interview Questions
|
Database concepts Interview questions -
Part 2
<<Previous
Next>>
Part 1 |
Part 2 | Part 3 | Part 4
Question - Define SQL.
Answer
Structured query language, SQL is an
ANSI standard language that provides commands to access and
update databases.
Question - Explain the difference between DBMS and
RDBMS.
Answer
DBMS offers organized way
of storing, managing and retrieving information.
RDBMS provides all features of DBMS with added referential
integrity concept.
Question - What are E-R diagrams?
Answer
E-R diagrams, i.e. Entity-Relationship diagram represent relationship between various
tables in the database.
Question - Explain the types of relationships in database.
Answer
One-to-one
One to one is implemented using
single table by establishing relationship between same type of
columns in a table.
One-to-many
Implemented using two tables with primary key and
foreign key relationships.
Many-to-many
Implemented using a junction table.
The keys
from both the tables form composite primary key of the junction
table.
Question - What are the benifits of normalizing database?
Answer
It helps to avoid duplicate entries.
It
allows saving storage space.
It enhances the performance of
queries.
Question - What is normalization?
Answer
It is the process of organizing data
into related table.
To normalize database, we divide database
into tables and establish relationships between the tables.
It
reduces redundancy. It is done to improve performance of query.
Question - What is denormalization?
Answer
The process of adding redundant data
to get rid of complex join, in order to optimize database
performance. This is done to speed up database access by moving from
higher to lower form of normalization.
Question - Explain DML and DDL statements.
Answer
Data definition language is used to
define and manage all attributes and properties of a database.
Most DDL statements include following
commands
CREATE
ALTER
DROP
Data Manipulation Language
Data manipulation language is used
to select, insert, update, and delete data in the objects defined
with DDL.
|
|
|
|
|