Question Discussion & Solution

Concept:

The GROUP BY statement groups rows that have the same values into summary rows, like "find the number of customers in each country".

The GROUP BY statement is often used with aggregate functions (COUNT, MAX, MIN, SUM, AVG) to group the result-set by one or more columns.

GROUP BY Syntax

SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
ORDER BY column_name(s);

The ORDER BY keyword is used to sort the result-set in ascending or descending order.

The ORDER BY keyword sorts the records in ascending order by default. To sort the records in descending order, use the DESC keyword.

ORDER BY Syntax

SELECT column1, column2, ...
FROM table_name
ORDER BY column1, column2, ... ASC|DESC;

The correct answer is World Wide Web.

Key Points

• Web service is a standardized medium to propagate communication between the client and server applications on the WWW (World Wide Web). 
  • A web service is a software system that supports interoperable machine-to-machine interaction over a network.
  • It has an interface described in a machine-processable format (specifically, Web Service Definition Language, or WSDL).
  • Web services fulfil a specific task or a set of tasks.
  • The nature of the interface hides the implementation details of the service so that it can be used independently of the hardware or software platform on which it is implemented and independently of the programming language in which it is written.

Additional Information

• A protocol is a set of rules or procedures for transmitting data between electronic devices, such as computers.
• The protocol that is used for transferring both text and binary files over the Internet is File Transfer Protocol (FTP).
• Hypertext Transfer Protocol (HTTP) is a protocol for transmitting hypermedia documents, such as HTML.
• Hypertext Transfer Protocol Secure (HTTPS) is a secure version of the HTTP protocol that uses encryption and authentication.

Concept:

ER model describes data as entities, relationships, and attributes. It is a high-level conceptual data model. This model is used to define the data elements and relationships for a specified system.

Entity:

The entity is a thing in the real world with an independent existence. An entity may be an object with physical existence. For example particular person, car or it may be an object with a conceptual existence For example company, job, etc.

Attributes:

Each entity has attributes – the particular properties that describe it.

Relationship:

It is used to describe the relation between two entities.

Explanation:

E-R Diagram is design level task and Relational model is implementation.

The relational model is implemented from E-R Diagram and in this, it gets rid of the multivalued attributes.

Relations produced from the E - R Model will always be in 1NF, that is, Simple atomic values with non-multivalued attributes.

NOTES:

Copper is a type of metal similarly, rupee is a currency of India.

All are divisible by 10 except 25.