SQL Tutorial

• What is SQL
• What is RDBMS
• Commonly Used Relational Databases
• SQL Syntax
• SQL Data Types
• SQL CREATE DATABASE
• SQL DROP DATABASE
• SQL USE
• SQL CREATE TABLE
• SQL DROP TABLE
• SQL RENAME TABLE
• SQL INSERT INTO
• SQL SELECT
• SQL WHERE
• SQL AND and OR
• SQL UPDATE
• SQL DELETE
• SQL LIKE
• SQL TOP
• SQL ORDER BY
• SQL GROUP BY
• SQL DISTINCT
• SQL Constraints
• SQL NULL
• SQL NOT NULL
• SQL DEFAULT
• SQL UNIQUE
• SQL Primary Key
• SQL Foreign Key
• SQL CHECK
• SQL INDEX
• SQL JOIN
• SQL INNER JOIN
• SQL LEFT JOIN
• SQL RIGHT JOIN
• SQL FULL JOIN
• SQL SELF JOIN
• SQL CROSS JOIN
• SQL UNION and UNION ALL
• SQL AS
• SQL ALTER TABLE
• SQL TRUNCATE TABLE
• SQL View
• SQL HAVING
• SQL Transaction
• SQL Temporary Tables
• SQL Clone Table
• SQL Sub Query
• SQL AUTO_INCREMENT
• SQL Injection

Commonly used relational databases

Relational databases are a fundamental component of information systems across nearly all industries. They use a structured data model with tables containing rows and columns. Here are some of the most commonly used relational databases:

1. MySQL: MySQL is a popular open-source relational database management system (RDBMS) owned by Oracle. It's widely used for web databases, especially for PHP applications. MySQL follows a client/server model.

2. PostgreSQL: PostgreSQL is a powerful, open-source object-relational database system that is known for its robustness and compliance with SQL standards. It supports complex queries and provides the ability to use various programming languages without recompilation.

3. Oracle Database: Oracle Database is a multi-model RDBMS produced and marketed by Oracle Corporation. It's a highly scalable and reliable solution, widely used in large enterprises for mission-critical applications.

4. SQLite: SQLite is a C library that provides a lightweight, disk-based database. It allows accessing the database using a nonstandard variant of the SQL query language. SQLite is embedded and hence it becomes an integral part of the application that uses it.

5. SQL Server: Microsoft's SQL Server is a comprehensive database server and information platform offering a range of management tools, extensive support for data processing, and advanced security features. It's largely used in enterprise environments.

6. MariaDB: MariaDB is an open-source RDBMS developed by the original developers of MySQL. It's designed to be a drop-in replacement for MySQL, guaranteeing complete compatibility.

7. IBM DB2: DB2 is a collection of data management products built by IBM. It offers advanced features like multi-node clustering, storage optimization, workload management, and more.

8. Sybase: Now owned by SAP, Sybase is an enterprise-level RDBMS. It's widely used in technology and financial sectors, known for its high performance in high transaction environments.

Each of these databases has their strengths and are well-suited to certain types of tasks. They all use SQL as their query language, although each might have their own specific extensions or features. It's also worth noting that each has different licensing models and costs associated with their use. Some are open-source (e.g., MySQL, PostgreSQL, SQLite, MariaDB) and can be used freely, while others require purchasing a license (e.g., Oracle, SQL Server).