What is SQL

SQL (structured query language) is the set of instructions used to interact with a relational database System. It is used for storing, manipulating and retrieving data stored in relational database. SQL is the standard language for Relation Database System.

SQL has three major components.

1) Data Definition Language (DDL)

Data Definition Language used to create and modify the structure of database objects in a database. These database objects include views, schemas, tables etc.

Commonly used Data Definition Languages are:

CREATE: This is used to create a new table, It has its own predefined syntax

e.g CREATE customer (customer_id int NOT NULL AUTO_INCREMENT, first_name varchar(255), email varchar(255),address varchar(255), PRIMARY KEY (customer_id) );

ALTER : This command is used to modify existing database table structure

DROP : A drop command deletes a table, index etc
e.g DROP TABLE customer

TRUNCATE : This command is used to empty a table

e.g TRUNCATE TABLE customer
RENAME : This command is used to rename a table
e.g RENAME customer TO customers_info

COMMENT : This statement is used to add a comment about a table or table column .

e.g COMMENT ON COLUMN customer.address IS ‘only customer city name’;

2) Data Manipulation Language (DML)

As the name specify data manipulation language is permitting users to manipulate data in a database .Common Manipulation operation are insert records into table, or need to change some record, or delete some record or perform any other actions on records in the database.

Commonly used Data Manipulation Languages are:

INSERT: INSERT is used to insert data in to database

e.g INSERT TO CUSTOMER(first_name, email, address) VALUES (‘sachin’,’[email protected]’,’Mubai’)

SELECT : SELECT is used to retrive data from database

e.g SELECT * FROM customer

UPDATE : UPDATE is used to updates existing data within a table

e.g UPDATE CUSTOMER SET first_name=’sachin ramesh’ WHERE email=’[email protected]

DELETE : DELETE is used to DELETE existing data within a table

e.g DELETE FROM CUSTOMER WHERE email=’[email protected]

CALL: call a PL/SQL or Java subprogram

CALL my_procedure(arg1 => 3, arg2 => 4)

LOCK TABLE : concurrency Control

e.g LOCK TABLES customer READ;

3) Data Control Language (DCL)

Data Control Language command is used to control access to data stored in a database. It is used to decide who can view this table and what kind of access like read, write, delete should be given to the other users.

Commonly used Data Control Languages are:

GRANT : GRANT provides the privileges to the users on the database.

GRANT INSERT ON customer TO vijay;

REVOKE : Revoke is used to cancel previously granted or denied permissions

e.g REVOKE INSERT ON customer FROM vijay;

How to find the rank of a website

Every website owner and the internet user has the desire to know about the rank of a website.But it is difficult for a third party to analysis full traffic of a website and based on that ranking a website. Fortunately we have lot of website traffic estimation services that is producing better result.It will be helpful for competitive analysis for website owner, finding fraud for internet user, analysis research for SEO team and for designing better marketing criteria for marketing team.

How to find the rank of a website for this we have lot of website,here i am listing only few of them

1) Alexa :- This is the number one site to find the rank of a website and this is most popular also.Almost all are using alexa-com for website anylysis, it will produce almost all details about a website .


see the below image checking the rank of google.


2) Similarweb :-  This is another site for finding the rank of a website.it is also displaying the detailed traffic report for the list of country based on the traffic .


see example of google in similarweb





You Tube Go, a new app from google for videos sharing and Offline video

Today in the event ‘Google For India’  held in New Delhi, Google announced “You Tube Go” ,a brand new app to enjoy and share videos.Built for the next generation of users to enjoy the power of YouTube. Maximize your fun without burning up your data.This app can use for videos sharing and Offline videos.It is created primarily for India.YouTube product management VP Johanna Wright says in a statement. “YouTube Go was designed and built from the ground up with insights from India, in order to bring the power of video to mobile users in a way that is more conscious of their data and connectivity, while still being locally relevant and social.”

Here is the official site link of You Tube Go http://youtubego.com/signup/

here they are saying “This app is coming soon!”, but not mentioned exact live release date.They said it will produce better result in 2G speed also.