Open
SQL Server
Can only run on Windows, not the slightest opening, operating system stability to the database is very important. Windows9X series emphasizes the desktop applications, NT server is only suitable for small and medium enterprises. And the Windows platform reliability, security and scalability is very limited. It is not as proven as Unix, especially in the processing of critical business data.
Oracle
Can run on all major platforms (including Windows). Fully support all the industry standard. With a completely open policy. Allows customers to choose the most suitable solution. Full support of the developer.
DB2
Can run on all major platforms (including Windows). Most suitable for mass data. DB2 in the most widely used enterprise-class, 500 in the world's largest enterprises, almost 85% with DB2 database server, and domestic to 97 years accounted for about 5%.
Scalability, parallelism
SQL Server
Parallel implementation and co-existence model is not mature. Difficult to deal with the growing number of users and data volumes. Flexibility is limited.
Oracle
By making a set of parallel server nodes share the same cluster in the work to expand the Window NT's ability to provide high availability and highly scalable cluster solution. If you can not meet the needs of WindowsNT, UNIX users can move in the database.
DB2
DB2 has a good parallel. DB2 database management to expand into the parallel, multi-node environment. Database partition is part of the database, including their own data, indexes, configuration files, and transaction logs. Database partition is sometimes referred to as node or database node.
Security
SQL server does not receive any security certificates.
Oracle received the highest level of ISO certification standards.
DB2 highest level of ISO certification standards.
Performance
SQL Server multi-user, poor performance
Oracle performance up to keep under WindowsNT TPC-D and TPC-C world record.
DB2 for data warehousing and online transaction processing, high performance.
Client support and application mode
SQL Server
C / S structure, only supports Windows clients, you can use ADO, DAO, OLEDB, ODBC connection.
Oracle
Multi-level network computing to support a variety of industry standard, can be ODBC, JDBC, OCI-peer network client connection.
DB2
Cross-platform, multi-layer structure, support ODBC, JDBC and other customers.
Simple
SQL Server
Simple operation, but only graphical interface.
Oracle
More complex, while providing GUI and command line, in Windows NT and Unix operating under the same.
DB2
Simple, while providing GUI and command line, in Windows NT and Unix operating under the same.
Use of risk
SQL Server
Completely rewrite the code, after a long test, and constantly delayed, many of the features takes time to prove. Not very compatible with earlier products. Use need to take some risk.
Oracle
Long development experience, fully backward compatible. Widely used. No risk.
DB2
In large enterprises have a wide range of applications, down to good compatibility. Little risk.