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This article mainly explains "what commonly used databases are there". The content of the explanation in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought and go deep into it slowly. Let's study and learn what commonly used databases are there.

Database meaning

A database is a warehouse that organizes, stores and manages data according to the data structure. It is a collection of organized, shareable and uniformly managed large amounts of data stored in the computer for a long time. A database is a collection of data stored together in a certain way, shared with multiple users, with as little redundancy as possible, and independent of the application. It can be regarded as an electronic filing cabinet-a place where electronic files are stored. Users can add, query, update, delete and other operations on the data in the file.

Introduction to common data 1. Oracle

Oracle is a relational database management system of Oracle, which has been in a leading position in the database field. It is one of the most popular relational databases in the world. It is a database scheme with high efficiency, good reliability and high throughput.

Advantages:

(1) Oracle is portable, can run on all major platforms (including Windows), and fully supports all industry standards. Adopt a fully open strategy so that customers can choose the most suitable solution. And full support for developers.

(2) to obtain the highest level of ISO standard authentication with high security.

(3) compared with other databases, Oracle has the highest performance. Holds the world records for TPC-D and TPC-C under the open platform.

(4) Multi-level network computing, which supports a variety of industrial standards, and can be connected by network customers such as ODBC, JDBC, OCI and so on.

(5) it is fully backward compatible, so it is widely used with low risk.

Disadvantages:

(1) High requirements for hardware

(2) the price is expensive.

(3) trouble in management and maintenance

(4) the operation is complicated.

2. SQL Server

SQL Server is a relational database management system developed by Microsoft (Microsoft), which is mainly used in large-scale management systems.

Advantages: (1) it has good compatibility with Microsoft's Windows operating system. (2) High performance design, which can make full use of the advantages of WindowsNT. (3) advanced system management, supporting Windows graphical management tools, supporting local and remote system management and configuration. (4) strong transaction processing function, using various methods to ensure the integrity of data. (5) support symmetrical multiprocessor architecture, stored procedure, ODBC, and independent SQL language. Disadvantages: (1) SQL Server can only run on Windows system, without the slightest openness. (2) No safety certificate has been obtained. (3) the performance is poor when there are multiple users. 3. MySQL

MySQL is an open source relational database management system, developed by the Swedish company MySQL AB, and belongs to Oracle products. It has attracted much attention because of its speed, reliability and adaptability. MySQL is one of the popular relational database management systems. In the application of WEB, MySQL is one of the best application software.

Advantages: (1) excellent performance, stable service, few abnormal downtime. (2) Open source code and no copyright restriction, strong autonomy and low cost. (3) it has a long history, and the community and users are very active. If you encounter problems, you can get help quickly. (4) the software is small, easy to install and use, and easy to maintain, and the cost of installation and maintenance is low. (5) support multiple operating systems, provide multiple API interfaces, and support multiple development languages. Disadvantages: (1) the biggest disadvantage of MySQL is its security system, which is mainly complex rather than standard, and only changes when rereading user rights by calling mysqladmin. (2) MySQL does not allow debugging of stored procedures, so it is difficult to develop and maintain stored procedures. (3) MySQL does not support hot backup. (4) the price of MySQL varies with platform and installation mode. 4. Access

Access is a small relational database management system released by Microsoft (Microsoft). It is a database management system that Microsoft combines the graphical user interface of the database engine with software development tools.

Advantages: (1) simple storage mode and easy maintenance and management. The objects of Access include tables, queries, forms, reports, pages, macros and modules, all of which are stored in the database file with the suffix (.mdb or .accdb), which is convenient for users to operate and manage. (2) Access is an object-oriented development tool, which is based on object-oriented development, which makes it easier to develop applications. (3) the interface is friendly and easy to operate. Access is a visualization tool, the style is exactly the same as Windows, users want to generate object applications, as long as use the mouse to drag and drop, very intuitive and convenient. The system also provides table generator, query generator, report designer and database wizard, table wizard, query wizard, form wizard, report wizard and other tools, which make it easy to operate, easy to use and master. (4) Integrated environment, which can deal with many kinds of data information. Access is based on the integrated development environment under the Windows operating system, which integrates various wizards and generator tools, which greatly improves the work efficiency of developers, so that the establishment of database, table creation, design user interface, design data query, report printing and so on can be carried out in a convenient and orderly manner. (5) widely supported, easy to expand and flexible. Access is not only a database that can only store data, but also can be used as a client development tool to develop database application systems. It can not only develop small software that is easy to use, but also can be used to develop large-scale application systems. Disadvantages: (1) concurrent processing is not supported. (2) the storage of the database is small and the security is not high enough. (3) Access is a small database, when the amount of data is too large, the performance of more than 100 megabytes (pure data, excluding forms, reports and other client objects) will become worse. (4) although it theoretically supports 255 concurrent users, it does not support that many at all. If the access is read-only, it is about 100 users, and if it is concurrent editing, it is about 10-20 users. (5) when the number of records in a single table exceeds one million, the performance will become worse, and if the poor design is added, this limit will be reduced. (6) cannot be compiled into an executable file (.exe). You must install the Access runtime environment before you can use it. 5. DB2

DB2 is a relational database management system that supports multimedia and Web developed by IBM Company in the United States. Mainly used in large-scale application systems, it has good scalability and can support from mainframe to single-user environment.

Advantages: (1) compared with MySQL and Oracle databases, DB2 provides high-level data utilization, integrity, security, recoverability, and small-scale to large-scale application execution ability, with platform-independent basic functions and SQL commands. (2) DB2 adopts data classification technology, which can easily download large data to database server, and make database localization and remote connection transparent. (3) it has a very complete query optimizer, which improves the query performance and supports multi-task parallel query. (4) it has good network support ability, each subsystem can connect more than one hundred thousand distributed users and activate thousands of active threads at the same time, which is more useful for large-scale distributed application systems. (5) DB2 can be used across platforms. Disadvantages: (1) there are many configuration files and parameters, and the naming is not standard. (2) it is not convenient to develop some DB2 products. (3) compared with Oracle, there are more commands, and it is not as good as the unified specification of Oracle. (4) due to the problem of its design framework, if users do not do enough to optimize the database itself and the application, then DB2 is prone to lock waiting. 6. PostgreSQL

PostgreSQL is a characteristic free database management system, and it can even be said to be the most powerful free software database management system. The database management system supports the most abundant data types in the world. It is the only free software in the free software database management system that supports transaction, sub-query, multi-version parallel control system, data integrity check and so on.

Advantages: (1) PostgreSQL follows the BSD protocol and is a completely open source, free, and very powerful relational database. (2) with PostgreSQL, there are many distributed cluster software, such as pgpool, pgcluster, slony, plploxy, etc., which are easy to do read-write separation, load balancing, data level splitting and so on, but these MySQL are difficult to implement. (3) the PostgreSQL source code is written clearly and is easier to read than MySQL, so many companies basically use PostgreSQL to do secondary development. (4) PostgreSQL is multiprocess, while MySQL is multithreaded. When the concurrency is not high, the processing speed of MySQL is fast, but when the concurrency is high, the overall processing performance of MySQL is lower than that of PostgreSQL on a single machine with multiple cores, because the threads of MySQL can not make full use of the power of CPU. (5) PostgreSQL has a powerful query optimizer to support complex query processing. Disadvantages: (1) for simple and heavy read operations, compared with other databases, PostgreSQL performance is low. (2) the expansion of PostgreSQL database takes a long time. Thank you for your reading, the above is the content of "what are the commonly used databases"? after the study of this article, I believe you have a deeper understanding of the problem of which commonly used databases are available. The specific use of the situation also needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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