What is SQL And RDBMS

What is SQL And RDBMS
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 MySQL, MS Access, Oracle, and SQL Server use SQL 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.
3. 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 defined as collection of rows and columns.
  • The horizontal lines are know as row or tupples or record.
  • The vertical lines are know as column or filed attributes.
  • The intersection or row and column is know as cell.
  • A cell is a place where you can store your data.
  • The other name of the table is celled as entry or class or object.

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