Introduction to SQL

tutorial and example
tutorial and example

SQL Introduction

  • SQL is Standard Query Language.
  • This language is used to communicate or interact with database.
  • In other words, SQL is used to access and manage data or information in the database by performing many different operations on data or tables or database.
  • According to the ANSI (American National Standards Institute), SQL is a standard language for RDBMS.
  • With the help of SQL, each user can get a different view of data as per their need.
  • SQL retrieves same data from a database and represents it in many different ways so that user can understand easily.
  • SQL is not case-sensitive.
  • In most of the cases, SQL syntax differs as the database changes.
  • Some most popular databases are: MySQL, ORACLE, DB2, SQL SERVER, MS ACCESS etc.

What is Database?

  • Database is a Data structure which stores organized data or information in the form of tables or files.
  • Database is nothing but a collection of tables/files/data.
  • Database is a collection of related data, which is organized in such a way so that storing, accessing, managing, modifying/updating of data becomes easier.

For example: Microsoft Excel is example of desktop database programs, which allows user to insert /enter data, store data and access that data whenever required.

What is DBMS?

DataBase Management System (DBMS) is a set of programs or software which allows creation, modification of database and at the same time it allows many different users to perform operations on database like store, modify, access etc.

RDBMS

Relational Database Management System is based on Relational model.

  • In RDBMS, everything is present in the form of relations.
  • Relation means Table.
  • Data is present in a tabular form.
  • Tables are interrelated with each other.
  • Dependencies/ Relationship between two tables is also represented through relation/table.

What is Difference Between DBMS and RDBMS ?

  • RDBMS applications store data in a tabular form whereas DBMS applications store data in the form of files.
  • DBMS can have Tables but there is no relation present in between tables.