What are the commonly used relational databases?

Relational database is a database based on the relational model, which uses mathematical concepts and methods such as set algebra to process data in the database. Various entities in the real world and various connections between entities are represented by relational models. The standard data query language SQL is a language based on relational databases. This language performs retrieval and operation of data in relational databases.

The relational model consists of three parts: relational data structure, relational operation set, and relational integrity constraints.

Simply put, a relational database is a database composed of multiple two-dimensional row and column tables that can be connected to each other. The current mainstream relational databases include Oracle, DB2, Microsoft SQL Server, Microsoft Access, MySQL, etc.

1. Oracle

Oracle is the world's first open commercial relational database management system launched in 1983. It uses standard SQL structured query language, supports multiple data types, provides object-oriented storage data support, has fourth-generation language development tools, and supports Unix, Windows NT, OS/2, Novell and other platforms. In addition to this, it has great parallel processing capabilities. Oracle products mainly consist of Oracle server products, Oracle development tools, Oracle application software, and also include computer-based database products. It mainly meets the needs of enterprises and institutions such as banks, finance, and insurance to develop large databases.

2, DB2

DB2 is a relational database management system developed by IBM in the United States. Its main operating environment is UNIX (including IBM's own AIX) , Linux, IBM i (formerly OS/400), z/OS, and Windows server versions.

DB2 is mainly used in large-scale application systems. It has good scalability, can support everything from mainframe to single-user environments, and can be applied to all common server operating system platforms. DB2 provides a high level of data utilization, integrity, security, recoverability, and execution capabilities for small to large-scale applications, with platform-independent basic functions and SQL commands.

DB2 adopts data classification technology, which enables mainframe data to be easily downloaded to LAN database servers, allowing client/server users and LAN-based applications to access mainframe data and localize the database. and remote connection transparency.

DB2 is known for having a very complete query optimizer, whose external connections improve query performance and support multi-task parallel queries. DB2 has excellent network support capabilities. Each subsystem can connect hundreds of thousands of distributed users and activate thousands of active threads at the same time. It is especially suitable for large-scale distributed application systems.

3. Microsoft SQL Server

SQL Server is a relational database management system launched by Microsoft. It has the advantages of ease of use, good scalability and a high degree of integration with related software, and can be used across a variety of platforms ranging from laptops running Microsoft Windows 98 to large multi-processor servers running Microsoft Windows 2012.

Microsoft SQL Server is a comprehensive database platform that provides enterprise-class data management using integrated business intelligence (BI) tools. The Microsoft SQL Server database engine provides more secure and reliable storage capabilities for relational and structured data, allowing you to build and manage highly available and performant data applications for your business.

4. Microsoft Access

Access is a relational database management system released by Microsoft. It combines the two features of MicrosoftJet Database Engine and graphical user interface, and is one of the system programs of Microsoft Office.

Access is a database management system that Microsoft combines the graphical user interface of the database engine with software development tools. It is a member of Microsoft Office and is sold separately in office versions including Professional and higher. On September 25, 2018, the latest Microsoft Office Access 2019 was released in Microsoft Office 2019.

MS ACCESS stores data in its own format in an Access Jet-based database engine. It can also directly import or link data stored in other applications and databases.

5. MySQL

MySQL is a relational database management system developed by the Swedish MySQL AB company and is currently a product of Oracle. MySQL is one of the most popular relational database management systems. In terms of WEB applications, MySQL is one of the best RDBMS (Relational Database Management System) application software.

MySQL is a relational database management system. A relational database stores data in different tables instead of placing all data in one large warehouse, which increases speed and flexibility.

The SQL language used by MySQL is the most commonly used standardized language for accessing databases. MySQL software adopts a dual licensing policy and is divided into community version and commercial version. Due to its small size, fast speed, low total cost of ownership, and especially the characteristics of open source, MySQL is generally chosen as the website database for the development of small and medium-sized websites.

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