MySQL, SQL Sever, Oracle

first, SQL Server
Advantages:
Ease of use, scalability for distributed organizations, data warehousing for decision support, integration with many other server software, and good price/performance ratio;
Provides flexibility for data management and analytics, allowing organizations to respond in a rapidly changing environment to gain a competitive advantage. From a data management and analytics perspective, it is important to turn raw data into business intelligence and take advantage of the opportunities that the web brings. As a complete database and data analysis package, SQL Server opens the door to success by rapidly developing next-generation enterprise business applications and winning the core competitive advantage of the enterprise. As a record-keeping provider of important benchmarks for scalability and speed awards, SQL Server is a database product with full web support, providing core support for Extensible Markup Language (XML) and the ability to query over the Internet and outside the firewall;

Disadvantages:
Openness: SQL Server can only run on Windows without the slightest openness operating system stability to the database is very important WINDOWS9X series products focus on desktop applications NT Server is only suitable for small businesses and the Windows platform relies on a very limited security and scalability like Unix-like tried to handle large databases especially;
Scalability parallelism: SQL Server parallel implementation and coexistence model and mature difficult to handle the increasing number of users and data volume scalability is limited;
Security: No security certificate was obtained.
Performance: SQL Server multi-user performance is good;
Client Support and Application mode: Client support and Application mode. Only support C/s mode, SQL Server c/S structure only support Windows customers with ADO, DAO, OLE DB, ODBC connection;
Use risk: SQL Server full rewrite code experienced long-term test-delay many functions take time to prove and are very compatible;
Second, Oracle
Advantages:
Openness: Oracle can run on all major platforms (including Windows) fully supports all industry standards with fully open policies to enable customers to choose the right solution for the developer to fully support;
scalability, parallelism: Oracle Parallel servers extend the WINDOWNT capability by enabling group nodes to share the same cluster work to provide a high-availability and high-scalability clustering solution WindowsNT can meet the needs of users to move the database unixoracle parallel server to a variety of UNIX platform cluster mechanism has a fairly high degree of integration;
Security: Obtain the highest certification level of ISO Standard certification.
Performance: Oracle performance remains open platform under the tpc-d and Tpc-c World records;
Client Support and Application Mode: Oracle Multi-level network computing supports a wide range of industrial standards such as ODBC, JDBC, OCI and other network customer connections
Use risk: Oracle's long-time development experience is completely backwards compatible with low risk of widespread application

Disadvantages:
The hardware requirements are very high;
The price is more expensive;
Management maintenance Trouble some;
The operation is more complicated and needs high technical content.

Third, MYSQL
Advantages:
Small size, fast speed, low total cost of ownership, open source;
Support multiple operating systems;
is an open source database that provides interfaces that support multiple language connection operations
MySQL's core program uses full multithreaded programming. Threads are lightweight processes that provide the flexibility to service users without excessive system resources. MySQL with multi-threaded and C language can easily make full use of CPU;
MySQL has a very flexible and secure access and password system. When the client connects with the MySQL server, all password transfers between them are encrypted, and MySQL supports host authentication;
Supports ODBC for Windows, supports all ODBC 2.5 functions and many other functions, can use access to connect MySQL server, so that the application is extended;
Support large database, can easily support the database of thousands record. As an open source database, it can be modified for different applications.
Have a very fast and stable thread-based memory allocation system, you can continue to use the surface without worrying about its stability;
MySQL offers a wide variety of different user interfaces, including command-line client operations, Web browsers, and a variety of programming language interfaces, such as c+,perl,java,php, and Python. You can use a pre-packaged client, or simply write a suitable application yourself. MySQL can be used for unix,windows, as well as OS/2 platforms, so it can be used on personal computers or servers;

Disadvantages:
Hot backup is not supported;
The biggest drawback of MySQL is its security system, which is mainly complex rather than standard, and only changes when Mysqladmin is called to reread the user's rights;
There is no stored procedure (Stored Procedure) language, which is the maximum limit for programmers accustomed to enterprise-grade databases;
The price of MySQL varies with the platform and installation mode. Linux MySQL is free if installed by the user himself or by a system administrator instead of a third party, and the third option must pay a license fee. Unix or Linux self-installing free, UNIX or Linux third-party installation fees;

The most basic one difference:

MySQL is free open source, how you use people will not charge your money. MySQL cross-platform, both Windows and Linux have a corresponding version.

SQL Server is charged, you can sue you for piracy at any time without giving money. SQL Server can only be used on Windows platforms.

Performance and security aspects, MySQL is stronger than SQL Server, MySQL management is a text command interface, to use tools to manage graphics, SQL Server is relatively simple point, itself is the graphical interface easy to start.

MySQL, SQL Sever, Oracle