mysql1.8,MySQL 5.1 英文手册 :: 1.8 MySQL Standards Compliance

1.8. MySQL Standards Compliance

This section describes how MySQL relates to the ANSI/ISO SQL

standards. MySQL Server has many extensions to the SQL standard,

and here you can find out what they are and how to use them. You

can also find information about functionality missing from MySQL

Server, and how to work around some of the differences.

The SQL standard has been evolving since 1986 and several versions

exist. In this manual, “SQL-92” refers to the

standard released in 1992, “SQL:1999” refers to the

standard released in 1999, “SQL:2003” refers to the

standard released in 2003, and “SQL:2008” refers to

the most recent version of the standard, released in 2008. We use

the phrase “the SQL standard” or “standard

SQL” to mean the current version of the SQL Standard at any

time.

One of our main goals with the product is to continue to work

toward compliance with the SQL standard, but without sacrificing

speed or reliability. We are not afraid to add extensions to SQL

or support for non-SQL features if this greatly increases the

usability of MySQL Server for a large segment of our user base.

The HANDLER interface is an example

of this strategy. See Section 12.2.4, “HANDLER Syntax”.

We continue to support transactional and nontransactional

databases to satisfy both mission-critical 24/7 usage and heavy

Web or logging usage.

MySQL Server was originally designed to work with medium-sized

databases (10-100 million rows, or about 100MB per table) on small

computer systems. Today MySQL Server handles terabyte-sized

databases, but the code can also be compiled in a reduced version

suitable for hand-held and embedded devices. The compact design of

the MySQL server makes development in both directions possible

without any conflicts in the source tree.

Currently, we are not targeting real-time support, although MySQL

replication capabilities offer significant functionality.

MySQL supports high-availability database clustering using the

NDBCLUSTER storage engine. See

Chapter 17, MySQL Cluster NDB 6.X/7.X.

We are implementing XML functionality beginning in MySQL 5.1,

which supports most of the W3C XPath standard. We plan to increase

support for XML as part of future MySQL development. See

Section 11.10, “XML Functions”.