Introduction to SQL

Structured Query Language

Introduction to Structured Query Language (SQL)

SQL Stands For Structured Query Language

By Using SQL We Can Interact with data like Data Storing, Insert, Update, Retrieve & Delete in database.

Structured Query Language (SQL) is designed for managing data in a relational database management system(RDBMS). SQL helps in storing, manipulating, and retrieving data in databases.

Best examples of SQL are MYSQL, SQL server.

Data is stored in databases it is collection of ( related ) data.

Earlier here for data store the File System is mostly used.

Disadvantages of File System

  • Difficult to maintain too many files
  • Data redundancy
  • Data inconsistency
  • Time consuming process
  • Searching is slow
  • Fetching various data with conditions
  • Recovery of data is hard
  • Security is less
  • The access of control is not in one hand

What is a Database ?

A database is a collection of related data organized in a way that data can be easily accessed, managed and updated. Any piece of information can be a data, for example name of your school database is actually a place where related piece of information is stored and various operations can be performed on it.

Database management system (DBMS)

A DBMS is a software that allows creation, definition and manipulation of database DBMS is actually a tool used to perform any kind of operation on data in database. DBMS also provides protection and security to database. It maintains data consistency in case of multiple users. Here are some example of popular DBMS MySQL, Oracle, Sybase, IBM etc.

What is a Relational Database (RDBMS)?

  A relational database management system (RDBMS) is a database management system based on relational model introduction by E.F. Codd. In relational model data is represented in terms of tuples (rows).

RDBMS is used to manage relational database. Relational database is a collection of organized set of tables form which data can be accessed easily. Relational Database is most commonly used database. It consists of number of tables and each table has its own primary key.

 

SQL (Structure Query Language)

  1. Using this Language you can interact with Database.
  2. You can execute a query using CMD or UI
  3. Topics included in SQL
    1. Data Type
    2. Different Categories Queries DDL, DML, DCL, TCL, DQL
    3. Constraints
    4. Different type of Joins

 

Some Concepts of DBMS

1. Database :- 

A database is an organized collection of data for one or more   purpose usually in digital form Ex. Collage Database.

2. Table :- 
Table is a set of data elements (value) that is organized using a   model of vertical columns ( Which are identified by their names )
and horizontal rows.

3. Field :- 
Individual columns of the database tables is called as “field”.

4. Record :- 
Individual Row of the database table is called as “Record” or   “Tuple”.

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