Introduction to major databases in Linux

Databases are the main part of Linux applications. Major databases on Linux include: Oracle, Sybase, DB2, and Informix; free software database: MySQL

Databases are the main part of Linux applications. Major databases on Linux include: Oracle, Sybase, DB2, and Informix; free software database: MySQL

Databases are the main part of Linux applications. Major databases on Linux include: Oracle, Sybase, DB2, Informix; Free Software databases: MySQL, PostgreSQL, and Msql.

Commercial database

As commercial databases have good technical support, I would like to give a brief introduction here.

(1) IBM DB2 ()

(2) Informix () Informix currently supports Informix SE, ESQL/C, Connect in Linux.

(3) Oracle () Oracle currently supports Oralce 8i and 9i in Linux.

(4) Currently, Sybase () supports Adaptive Server Enterprise 11.9.2 in Linux.

(5) Ingres () CA currently supports the Ingres II database in Linux.

Free Software Database

1. MySQL

MySQL is developed and maintained by Swedish company T. c. X. It is a real multi-user, multi-thread SQL database server. MysQL implements its functions in a Client/Server structure. It consists of a server daemon mysqld and many different client programs and libraries. SQL is a standardized language that makes it easier to store, update, and access information. MySQL features fast, robust, and easy to use. The official pronunciation of MySQL is "My Ess Que Ell" (not MY-SEQUEL ). Currently, the latest MySQL version is 4.04. The MySQL website is:, the MySQL logo is a little dolphin. See figure-1.

Figure-1

(1) Advantages of MySQL:

1. The core thread used is completely multi-threaded and supports multi-processor.

2. there are multiple column types: 1, 2, 3, 4, and 8-byte length self-owned symbols/unsigned integers, FLOAT, DOUBLE, CHAR, VARCHAR, TEXT, BLOB, DATE, TIME, DATETIME, TIMESTAMP, YEAR, and ENUM type.

3. It implements the SQL function library through a highly optimized class library and is as fast as they can achieve. Generally, there should be no memory allocation after the query initialization. No memory vulnerabilities.

4. SQL GROUP BY and ORDER BY clauses are fully supported. Aggregate functions (COUNT (), COUNT (DISTINCT), AVG (), STD (), SUM (), and MAX () are supported () and MIN ()). You can mix tables from different databases in the same query.

5. Supports LEFT 0 uter join and ODBC For ansi SQL.

6. All columns have default values. You can use INSERT to INSERT a subset of a table column. columns that do not explicitly specify values are set to their province-based values.

7. MySQL can work on different platforms. Supports C, C ++, Java, Perl, PHP, Python, and TCL APIs.

(2) Disadvantages of MySQL:

1. The biggest drawback of MySQL is its security system, which is mainly complicated and non-standard. In addition, it only changes when mysqladmin is called to re-read user permissions.

2. Another major drawback of MySQL is the lack of a standard RI (Referential Integrity-RI) mechanism; the lack of Rl restrictions (a fixed range limit on a given field) A large amount of data types can be used for compensation.

3. MySQL does not have a Stored Procedure language, which is the biggest restriction on programmers who are used to enterprise-level databases.

4. MySQL does not support hot backup.

5. The price of MySQL varies with the platform and installation method. Linux MySQL is free of charge if it is installed by the user or the system administrator instead of a third party. The third solution requires a license fee. Free installation for Unix or Linux, $200 for third-party installation for Unix or Linux,

$200 is required for an application component.