The understanding of several databases

When I saw this week's weekly article titled "About understanding and understanding of the database ", I suddenly felt that I could not do it, because I did not know what to write, my own understanding of the database and the database that I had access to, confined to the classroom, the teacher talked about the Microsoft Company's SQLServer2008, for the rest of the database itself is hearsay. So I am crazy on the Internet to find information, from different aspects of the current several mainstream database. Here to organize what you have learned to share to everyone. Of course , because SQLServer2008 himself with a lot of, so I will focus on how I feel about this database.

At present, the commercialized database management system takes the relational database as the leading product, the technology is more mature. Object-oriented database management system Although the technology is advanced, the database is easy to develop and maintain, but has not yet mature products. The leading relational database management system in the world is Oracle,Sybase,Informix, and INGRES. These products are supported on multiple platforms, such as UNIX,windows, and so on, but with a different level of support. Of course, this database, for the students at the stage of our more unfamiliar, but in the actual work in contact with more. But then, I will introduce you from several aspects, such as security, scalability, openness, operability, and application areas.

• Sql server

SQL Server is a relational database management system launched by Microsoft Corporation. It can be used across multiple platforms, from laptops running Microsoft Windows 98 to large multiprocessor servers running Microsoft Windows. Is the most popular database on the web for storing data, it has been widely used in e-commerce, banking, insurance, electricity and other database-related industries. The latest version is SQLServer2012. He can only run on Windows, and the stability of the operating system is important to the database. The parallel implementation and coexistence model is not very mature, it is difficult to deal with the increasing number of users and data volumes, scalability is limited. But because of its friendly interface, it makes it easier for developers to operate. It provides numerous Web and e-commerce features that make it easy to access Web data.

Its main features are as follows:

• Advantages:

2. A true client /server architecture in which the computer, which processes the application, requests the service, is called the client, and the computer that processes the database is referred to as the server.
4. Graphical user interface makes system management and database management more intuitive and simple; Provides a graphical interface for tables, views, and query definitions, a graphical interface using SQL language, server and database User Configuration in the graphical interface of query analyze.
6. Rich programming interface tools provide users with a greater choice of program design;SQL Server provides a rich application interface to access data from servers, with the main access methods:ODBC API,OLE DB, Transact-SQL and db-library, where clients can use these APIs as dynamic connection libraries and communicate with SQL Server servers through the client's network library. support for Web technology enables users to easily publish data from a database to a Web page;
8. you can draw data from a database table in the Web assistant, and you can bring data from the HTML into the database. SQL Server data can be automatically published on a Web page , and users can query the information stored in SQL Server through a common browser , so you can use the information stored in SQL Server to create a dynamic Web page.
10. SQL Server provides data warehousing capabilities: This feature is only available in Oracle and other more expensive DBMS.
12. Support for XML (extensive Markup Language, extended Markup Language)

• Disadvantages:

1. Openness: It can only run on Microsoft's Windows platform, without the slightest openness whatsoever.
2. Scalability, parallelism: the parallel implementation and coexistence model is immature, and it is difficult to handle the increasing number of users and data volumes with limited scalability.
3. Performance Stability:SQL Server performance can become poor and not stable when users connect for a long time.
4. Use risk:SQL Server completely rewrites the code, undergoes long-term testing, is constantly delayed, and many functions take time to prove. is not very compatible with earlier products. Use requires a certain amount of risk.
5. Client Support and Application mode: main support C/s mode.

• ORACLE:

When you bring up a database, the first company you think of IS Oracle (Oracle ). The company was founded in 1977 and was originally a company specializing in database development. Oracle has been a leader in the database industry. In 1984, the relational database was first transferred to the desktop computer. Then,Oracle5 pioneered the new concepts of distributed databases, client /server architectures, and more. The latest Oracle 12c increases the object technology and becomes the relational-object database system. Oracle is now one of themost widely used relational data systems in the world , covering dozens of models, including large, medium and small machines.

• Advantages:

2. Compatibility:Oracle products are standard SQL and tested by the U.S. National Standards and Technology Institute (NIST). compatible with IBM sql/ds,DB2,INGRES, idms/r, andmore.
4. Portability:Oracle's products can run on a wide range of hardware and operating system platforms. Can be installed in more than 70 different large, medium and small machines, can be in VMS,DOS,UNIX,windows and other operating systems under the work.
6. Connectivity:Oracle can be connected to a variety of communication networks, supporting a variety of protocols (TCP/IP,DECnet,LU6.2, etc. ).
8. High productivity:Oracle products offer a variety of development tools that can greatly facilitate further development of the user.
10. Openness:Oracle's good compatibility, portability, connectivity and high productivity make Oracle RDBMS a good open
12. Oracle really implements row-level locks, andSQL Server claims to implement row-level locks, but you actually try, if not indexed, it is not.
14. Oracle's transaction log archiving is quite handy, and SQL Server is implemented with transaction log backups, and you also configure automated jobs to start the agent service.
16. Oracle's rich data dictionaries make it easy for DBAs to judge the various scenarios of a database, although SQL Server 2005 learns the characteristics of Oracle's data dictionaries, but is too different in terms of quantity and convenience. Personal feeling this is the most humane place for Oracle.
18. Oracle has more than a few types of triggers than SQL Server.

• Disadvantages:

1. More complex, the user interface is not friendly. For beginners, getting started has a certain degree of difficulty.

• Mysql:

MySQL is the most popular open source SQL database management system, developed, distributed, and supported by MySQL AB. MySQL AB is a MySQL developer-based business company, a second-generation open source company that uses a successful business model to combine open source values and methodologies. MySQL is a registered trademark of MySQL AB. MySQL is a fast, multi-threaded, multi-user, and robust SQL database server. MySQL server supports the use of critical tasks, heavy-duty production systems, or it can be embedded in a large configuration of software.

• Advantages:

2. It uses a core thread that is fully multi-threaded and supports multiple processors.
4. There are a variety of column types:1,2,3,4, and 8 byte length own/unsigned integer,FLOAT,DOUBLE,CHAR,VARCHAR,TEXT, BLOB,DATE, Time,DATETIME, TIMESTAMP, year, and enum types.
6. It implements a library of SQL functions through a highly optimized class library and is as fast as they can reach, usually without any memory allocations after the query is initialized. There is no memory leak.
8. Full support for SQL's GROUP by and ORDER by clauses that support aggregate functions (count (),count (DISTINCT),AVG (),STD (),SUM (), MAX () and MIN ()). You can mix tables from different databases in the same query.
10. Support for ANSI SQL left 0UTER join and ODBC.
12. All columns have default values. You can insert a subset of table columns with insert, and those columns that do not have a definite given value are set to their default values.
14. MySQL can work on different platforms. Supports C,C + +,Java,Perl,PHP,python, and TCL APIs.

• Disadvantages:

1. The biggest drawback of MySQL is its security system, which is mostly complex rather than standard, and only changes when Mysqladmin is called to reread user rights.
2. Another major drawback of MySQL is the lack of a standard RI (referential integrity-ri) mechanism; thelack of RL limitations (a fixed range limit on a given field domain ) Can be compensated by a large number of data types.
3. MySQL does not have a stored procedure (Stored Procedure) language, which is the biggest limitation for programmers accustomed to enterprise-grade databases.
4. MySQL does not support hot backups.
5. The price of MySQL varies with the platform and installation mode.

The above is I through the collection of information and some of the feelings of self-collation of several databases on the understanding.

Data Source:
http://blog.csdn.net/keywaytang/article/details/7544002

http://blog.renren.com/share/253251848/11925571593

Http://blog.chinaunix.net/uid-7374279-id-2057575.html

Http://www.educity.cn/develop/123622.html

http://blog.163.com/[email protected]/blog/static/130059154201001443631158/

The understanding of several databases