SQL is a standard language for accessing and manipulating databases. SQL is one of the most in-demand tech skill used across many industries. What is SQL?SQL stands for Structured Query LanguageWhat Can SQL do?SQL lets you access and manipulate databasesSQL can execute queries against a databaseSQL can retrieve data from a databaseSQL can insert records in a databaseSQL can update records in a databaseSQL can delete records from a databaseSQL can create new databasesSQL can create new tables in a databaseSQL can create stored procedures in a databaseSQL can create views in a databaseSQL can filter data returned from a databaseSQL can sort data returned by a database. SQL can be used to truncate and drop tables. PostgreSQL is a powerful, open source object-relational database system. PostgreSQL is an advanced, enterprise-class, and open-source relational database system. PostgreSQL supports both SQL (relational) and JSON (non-relational) querying. PostgreSQL is a highly stable database backed by more than 20 years of development by the open-source community. PostgreSQL is used as a primary database for many web applications as well as mobile and analytics applications. MySQL is a relational database management system based on SQL Structured Query Language. The application is used for a wide range of purposes, including data warehousing, e-commerce, and logging applications. The most common use for mySQL however, is for the purpose of a web database. SQL SERVER is a relational database management system (RDBMS) developed by Microsoft. It is primarily designed and developed to compete with MySQL and Oracle database. SQL Server supports ANSI SQL, which is the standard SQL (Structured Query Language) language. However, SQL Server comes with its own implementation of the SQL language, T-SQL (Transact-SQL).T-SQL is a Microsoft propriety Language known as Transact-SQL. It provides further capabilities of declaring variable, exception handling, stored procedure, etc. SQL Server Management Studio (SSMS) is the main interface tool for SQL Server, and it supports both 32-bit and 64-bit environments.