SQL Tutorial

By | May 20, 2020

SQL stands for Structured Query Language and it is a standard language that is used to create Database. It’s always been a debate that sometimes SQL also defined as a programming language for Relational Database, but SQL is a Query language that is used to create a Relational Database. Apart from creating a Database we can also retrieve and manage data in the database using an SQL application.

SQL is a Language more like a concept such as High-Level languages, there are other application and programs which are known as RDBMS (Relational Database Management Systems) which use the concept of SQL to create and manipulate databases, you must have heard of MySQL which is an open-source RDBMS  that uses SQL concepts.

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So, if someone asks you what is the difference between SQL and MySQL, you should answer that SQL is a concept of Relational Database and MySQL is a Relational Database Management System which is used to create the database. Apart from MySQL, there are many other RDBMS such as PostgreSQL, SQLite, Oracle, etc.

What is SQL?

SQL stands for Standard Query Language and in Computer Science we pronounce SQL as a sequel. ANSI defined SQL as a Standard language for Relational Database, keep in mind that SQL is not a programming language though there is always a debate of SQL being a programming language ANSI and most developers define it as a query language.

In SQL we use SQL statements and these stalemates are termed as query, which performs various task such as create, update, retrieve and delete data between various tables present in the database, in short, we can say that SQL commands are used to perform CURD operations.

SQL itself is used by various applications and there are various Relational Databases Management System such as Oracle, MySQL, SQLite, and PostgreSQL which use SQL concepts to perform all the live actions, and in general, we call all these RDBMS as SQL.

However, all these different RDBMS have different properties and comes with their own respective extension which helps them run on a specific application, but they all contain similar SQL commands like “Select”, “Insert”, “Update”, “Delete”, “Create”, and “Drop”.

SQL History

  • It is developed by Donald D.Chamberlin and Raymond F. Boyce at IBM in the early 1970s.
  • Initially, SQL released as SEQUEL (Structured English Query Language), and it was used to manipulate and retrieve data stored in IBM’s original quasi-relational database management system.
  • Later SEQUEL changed to SQL because it was a trademark of a UK based company.
  • In 1986 ANSI recognise SQL as a standard language for Relational Database.

Why Learn SQL?

Before Learning any specific Language or Technology in computer science you should know why are you learning it?, does it have any use in the future? or where can I use it? Let’s tackle these questions.

We all know that most of the tech giants have shifted their business model to data, and now in the era of AI, Machine Learning, Cloud computing, and Data Science, Data has become the most important asset for any organization, and SQL provides an efficient way to organize, create and retrieve data between databases.

There are many methods of storing a Data but right now Relational Databases are the most popular technique to store data, in Relational Database Systems we store data in tables using row and columns, and for this, we use SQL, which is a Standard Language for Relational Database Systems, and all the Relational Database Management Systems (RDBMS) such as MySQL, MS Access, Oracle, Sybase, Informix, Postgres, and SQL Server use SQL as their standard database language.

Currently, SQL is ruling the market of Database management and it does not seem that it’s going to obsolete anytime soon.

What can SQL Do?

Here are some major applications of SQL, which describe the overall objective of SQL.

  • SQL can Create Databases.
  • It can insert data in Database
  • It can retrieve data from the database
  • we can update data using SQL.
  • It can create multiple tables in a single database.
  • We can also create views using SQL
  • We can also delete data from the database.
  • With SQL we can execute queries against a Database

Prerequisites to Learn SQL

Before learning SQL or any of its tool, you should be aware of Relational Database Systems and some of its concepts, however, to learn MySQL or any other RDBMS you do not need the expert knowledge of SQL, just follow this series of tutorial and also practice at your local system.

For most of the RDBMS, the SQL syntax is similar but for this tutorial, we are going to use the MySQL RDBMS.

SQL Commands

In SQL we write the commands and these commands used to perform the various operations. There are various SQL commands and SQL has classified of its command into 3 major categories.

  • DDL
  • DML
  • DCL

1. Data Definition Language:

DDL commands are used to define the database schema, with DDL commands we describe the database structure:

Major DDL commands:
  • CREATE
  • ALTER
  • DROP
  • ALTER
  • RENAME
  • COMMENT

2. Data Manipulation Language (DQL)

DML commands are used to show and manipulate data between the database.

Major DML commands:
  • Select
  • Update
  • Insert
  • Delete

3. Data Control Language

DCL commands are used to deal with the permission and authority control of the database systems.

Major DCL commands:
  • GRANT
  • REVOKE

SQL Tutorial Quick Summary

  • SQL stands for Standard Query Language
  • It is a Query Language, but some of the developers refer to it as a programming language because it contains some of the concepts of high-level programming language.
  • RDB stands for Relational Database.
  • A Database is a collection of Data.
  • In a relational database, Data is stored in the table using rows and columns.
  • SQL is the standard language used for Relational Database.
  • MySQL, Oracle, PostgreSQL are the Relational Database Management Systems which are used to create and modify the relational database.

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