SQL-Tutorial

In this SQL tutorial, you’ll learn all the basic to advanced SQL concepts like SQL queries, SQL join, SQL injection, SQL insert, and creating tables in SQL. SQL is easy to learn, there are no prerequisites to learning SQL.

So, SQL is a standard database language used to access and manipulate data in databases. SQL stands for Structured Query Language. It was developed by IBM Computer Scientists in the 1970s. By executing queries SQL can create, update, delete, and retrieve data in databases like MySQL, Oracle, PostgreSQL, etc. Overall, SQL is a query language that communicates with databases.

Why to Learn SQL?

SQL helps you to easily get information from data with high efficiency. To manipulate the data in databases like Create, Read, Edit, and Delete, we use SQL queries. Users can interact with data stored in relational database management systems. Anyone who knows the English language can easily write SQL queries. Some of the key features of SQL are given below:

• Without a lot of coding knowledge, we can manage a database with SQL.
• SQL works with database systems from Oracle, IBM, Microsoft, etc.
• Simple and easy to learn.
• SQL is an ANSI and ISO standard language for database manipulation.
• SQL retrieves large amounts of data very fast.

Pre-Requisites to Learn SQL

If you want to learn SQL then, this free SQL tutorial is quite easy to understand because, during the development of this course, we tried our best to provide the best resource to clear your SQL concept.

But we assume that you are already aware of the basic conceptions of computer science, like databases and its types.

So, if you have basic knowledge of RDBMS, then this SQL tutorial provides you with enough knowledge to master SQL.

Table of contents

1. SQL Basics
2. Database In SQL
3. Table In SQL
4. SQL Queries
5. SQL Clauses
6. SQL Operators
7. SQL Aggregate Functions
8. SQL Data Constraints
9. SQL Joining Data
10. SQL Functions
11. SQL Views
12. SQL Indexes
13. SQL Miscellaneous Topics

Important Note

[!IMPORTANT]

In SQL, keywords are not case-sensitive, meaning "__update__" is equivalent to "__UPDATE__".

Important Commands

Here is the list of some important SQL Commands:

Command	Description
SELECT	Used to retrieve data from a database.
INSERT	Adds new records or rows to a table.
UPDATE	Modifies existing records in a table.
DELETE	Removes records from a table.
CREATE TABLE	Creates a new table in the database.
ALTER TABLE	Modifies an existing table structure.
DROP TABLE	Deletes a table from the database.
CREATE INDEX	Creates an index on a table column to speed up data retrieval.
DROP INDEX	Removes an index from a table.
CREATE VIEW	Creates a virtual table based on the result of a SQL statement.
DROP VIEW	Deletes a view from the database.
INSERT INTO SELECT	Inserts data from one table into another based on a query.
TRUNCATE TABLE	Removes all records from a table, but keeps the table structure intact.
ALTER TABLE ADD CONSTRAINT	Adds a constraint to a table after it has been created.
GRANT	Gives specific privileges to database users.
REVOKE	Removes specific privileges from database users.
COMMIT	Saves all changes made since the last commit.
ROLLBACK	Discards all changes made since the last commit.
BEGIN TRANSACTION	Starts a new transaction.
SET TRANSACTION	Sets characteristics for the transaction.

Applications of SQL

In data-driven industries where managing databases is very important in regular, Here are some important SQL applications.

• To support client/server architecture, software engineers use SQL to establish the connection between the back-end and front-end.
• SQL can also be used in the 3-tier architecture of a client, an application server, and a database.
• SQL is used as a Data Definition Language(DDL) in which we can independently create a database, define the structure, use it, and discard it when its work is done.
• SQL is used as a Data Manipulation Language(DML) in which we can enter data, modify data, and extract data.
• SQL is used as a Data Control Language(DCL) it specifies how we can protect our database against corruption and misuse.