Introduction to SQL

SQL is a standard computer language for accessing and manipulating databases.

SQL is a standarad language and it follows the ANSI standards(American National Standarads Institute) but there are different versions of SQL language.

 What is SQL?

  • SQL stands Structured Query Language
  • SQL allows you to access a database
  • SQL follows the ANSI standard
  • You can use SQL to  execute queries against a database
  • You can use SQL to  retrieve data from a database
  • You can use SQL to  insert new records in a database
  • SQL can also delete records from a database
  • You can use SQL to update records in a database
  • SQL is very easy to adapt and learn

RDBMS:

When you use SQL in your website you need an RDBMS program such as SQL Server, MySQL, MS Access etc.

RDBMS represents Relational DataBase Management System. For SQL and all latest database systems like MySQL Serever, Oracle, MySQL, Microsoft Access etc. RDBMS is the basis.

The data that is stored in RDBMS database is known as tables. A table is consist columns and rows and it these columns and rows is a collection of data entries.

Some Standard SQL Queries :

SQL (Structured Query Language) is a language  for executing queries from database. But the SQL language also includes syntax to insert, update and delete records.

These all query and update commands are together form the Data Manipulation Language (DML) part of SQL:

SELECT – extracts data from a database table

UPDATE – updates data in a database table

DELETE – deletes data from a database table

INSERT INTO – inserts new data into a database table

CREATE DATABASE – creates a new database

ALTER DATABASE – modifies database

CREATE TABLE – creates a new table in database

ALTER TABLE –  modifies the table in database

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