Introduction to SQL (DBMS & RDBMS)

 Introduction to SQL

Type of Languages:-

1.General Purpose Language
2.Domain Specific Language

1. General Purpose Languages -

     Example :-  C , C++ , JAVA , PYTHON , RUBY , C# , Kotlin , R , TCL .......etc.

2. Domain Specific Language -SQL is one of the domain specific language of them are in use and few are still in research and development. 

      The Query Language which are use as follow -

       SQL

       MYSQL
      P l SQL

      PostgreSQL

      Mongo DB (Non SQL) - Unstructured SQL

      SQL Server

      SQL Lite

History of SQL - EF CODD who was a mathematical had propose a mathematical model regarding data. The same mathematical model later implemented by -

Roymand Boyce

donold chomborlin

SQL was initially known as SEQUEL  (Simple Query Language).

The name got change because the UK base aircraft company was having tread moral of SEQUEL. The name was change,

-SQL was global acceptance in 1986.

-The recent update for SQL come in 2016.

Why do we use SQL - 

• We use SQL to interact or communicate with data. Which is stored in database for data operation or data manipulation.
• We use SQL to write query. (Query is set of instruction written in normal English which can be understand by the database)

DATA

Data is not information data is a part of information.

Data is raw fact which describe the  characteristics of an object or an entity .

Characteristics is also known as attribute.

Let Consider 

    The object an entity which is employee the are several characteristics or attribute for the employee.

Example -  

Database is place where we store data in the organization way for easy retrieval. 

DBMS 
(Database Management System)

DBMS is a software which is use to interact with the data which stored in database for data manipulation using query language.

Disadvantages-

1. Data in DBMS is stored in the form of flat files.
2. It is difficult to identify the duplicate data.
3. It is difficult to remove the duplicate data.
4. Normalization is not possible.(Normalization is not possible duplicate data). 

RDBMS
(Relational Database Management System)

RDBMS - It is software which is use to interact with data which is stored in database for data manipulation using query language and relation model.

Advantages -

1. Data in RDBMS is stored in the from of table.
2. It is easy to identify  the duplicate data.
3. It is easy to remove the  duplicate data.
4. Normalization is possible

Database can not have two table with same name.

Table - It is logical representation of rows and columns.

Cell - Cell will be formed when a rows combines a column or vice versa.

cell is small component of table.

EF CODD Rules

1. Data in RDBMS should be stored in the form of table.
2. There can be multiple table in database.
3. The cell should be atomic and singular.
4. The table should follow a relation model.

Database can not have two table with the same name.

Relation Model -

We can establish the relation between two or more than two table.