What is SQL, RDBMS and Database System.

SQL (Structure Query Language) was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce in the early 1970s. This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasi-relational database management system.
SQL (Structure Query Language) is a non-procedural language. SQL are used for access and manipulate data in databases. SQL is an ANSI (American National Standards Institute) standard language.
What is SQL:  SQL stand for Structured Query Language, which is a computer language for storing, manipulating and retrieving data stored in a relational database. It is a language for Relational Database System. All the Relational Database Management Systems (RDMS) like MysoL, MS Access, Oracle, and SQL Server use soL as their standard database language. Also, they are using different dialects, such as - 
  • MS SOL Server using T-SQL,
  • Oracle using PL/SQL,
  • MS Access version of SQL is called JET SQL (native format) etc. 
SQL Sub Language
 SQL is mainly divided into four sub language 
  • Data Definition Language(DDL) 
  • Data Manipulation Language(DML) 
  • Transaction Control Language(TCL) 
  • Data Control Language(DCL) 
Only for remember
  •  You can remember all these command like below: DDI Commands "dr. cat" d-Drop, r-Renamc, e-Crcate, a-Alter, L-Truncate. 
  • DML commands "sudi". s-Select, u-Update, d-Delete, i-Insort. 
Why need of SQL
 SQL is so popular for following advantages- 
  • To create new databases, tables. 
  • To insert any records in database 
  • To delete records from database 
  • To update records in database 
  • To retrieve data from database .
Features of SQL 
  • SQL is not a case sensitive language. 
  • Every commands in SQL should ends with semicolon(;)
  • SQL can also called as sequel (SEQUEL). 
  • It is an ANSI (American National Standards Institute) standard language.
Limitation of SQL

  •  SQL does not support conditional and looping statements. 
  •  When user performs any wrong transaction, SQL always gives system defined error message. 
  • It cannot support to execute more than one statement at a time, so it increases the network traffic.
  •  SQL does not support the code re-usability;, it means you need to write insert, delete, update, select command each and every time. 
  • sQL does not support procedure language features such as code re-usability and molecularity and some other features of oops. 
To Overcome all these above limitation we use PL/SQL

What is RDBMS?
RDBMS stands for Relational Database Management System. All modern RDBM database management systems like SOL, MS SOL Server, Oracle, MySQL, IBM DB2, and Microsoft Access are based on RDBMS.
 RDBMS was developed by a Jermen scientice Mr. E.F codd at 1970 this model was developed on the basis of a mathematical concept called relational algebra.
Relations are classified into three types, they are;
1.one to one Relationship 
In the relationship one object have only relation with another object.
 2. One to may or many to one relationship
in the relationship one subject have relation with many other object.
Many-many Relationship
In this relationship many object has the relationship with many other object.
Properties of RDBMS

  • Data should be stored in the from of table.
  • A table can be deifined as collection of rows or tupples or record.
  • The vertical lines are knows as column or field or attributes.
Database- Database is the collection of tables, using sql you can insert or retrieve data from database. First you need to  create database, you can also drop a database.
Syntax to create database 
Syntax
CREATE DATABASE DataBase_Name;
Note: In MySql, first ypu need to create database then create table , but in case of Oracle no need to create database , you can create table directly.

Rename Database 
By using SQL RENAME DTATABASE Statement you can change the name of database Following syntax are use for rename database.
Syntax
RENAME DATABASE old_db_name TO new_db_name;

Drop Database 
Drop statement is used to delete or remove indexes from a table in the database . yes can also delete existing database.
Syntax
DROP DATABASE dataBase_Name;

(All details about this i will Update soon)


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