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大连交通大学信息工程学院

毕业设计(论文)外文翻译

学生姓名罗旭专业班级计算机08-2班指导教师王影魏琦职称高工讲师所在单位信息科学系计算机教研室

教研室主任宋丽芳

完成日期 2012 年 4 月 13 日

MySQL

MySQL's original developer intent is to use the mSQL and their rapid low-level routines ( ISAM ) to connect to form. After some tests, the developers concluded: mSQL and there is no need for them so fast and flexible. This led to a use almost like mSQL API interface for their database of the new SQL interface, so, the API is designed to allow for use on the mSQL to write the third party code easier to transfer to MySQL.

The name MySQL is how come is not clear. Basic guide and a large number of libraries and tools with the prefix "my" has had more than 10 years, and no matter what,co-founder of MySQL AB Monty Widenius The daughter also named My. The two which one it was given the name MySQL remains a mystery, including developers, also do not know.

MySQL Dolphins Logo name is" sakila", which is composed of a MySQL AB founder from the users in the" dolphin named" contest suggested a name table as select. The winning name is made from Africa and Swaziland's open source software developer Ambrose Twebaze. According to Ambrose, Sakila from a SiSwati Swaziland dialect, but also in the Ambrose 's home town of Uganda, near Tanzania's Arusha is one of the town's name.

And other large databases such as Oracle, DB2, SQL Server compared to MySQL, has its own disadvantages, such as small size, limited functionality ( MySQL Cluster function and efficiency are relatively poor ), but it did not reduce its popularity. For the average individual users and small and medium enterprises, the functionality provided by MySQL is more than sufficient, and because MySQL is open source software, thus can greatly reduce the total cost of ownership.

LAMP:

The current Internet popular website architecture is LAMP ( Linux + Apache + MySQL + PHP / Perl / Python ) and LNMP ( Linux + Nginx + MySQL + php / Perl / Python ), which uses the Linux as the operating system, Apache and Nginx as the Web server, MySQL as the database, PHP / Perl / Python as a server-side script interpreter. As a result of the four software are free or open source software ( FLOSS ), so use this way without spending a dime ( except artificial cost ) to establish a stable, free website system.

MyISAMMysql default database, the most commonly used. Have a high insertion, search speed, but does not support transactions InnoDB transactional database preferred engine, support for ACID affairs, support row-level locking BDB from Berkeley DB, transactional database for another option, support for COMMIT and ROLLBACK and other transaction characteristics of Memory all of the data in memory storage engine, with a high insertion, update and query efficiency. But it will take and data is proportional to the amount of memory space. And its content in the Mysql restart lost when Merge will be a certain amount of MyISAM combined into a whole, in the large scale data storage is useful when

Archive is very suitable for storing a large number of independent, as history data. Because they don't often been read. Archive has efficient insertion speed, but its effect on query support relatively poor Federated different Mysql server logic together, form a complete database. Very suitable for distributed application of Cluster / NDB high redundancy storage engine, using multiple data machine combined to provide services to improve overall performance and safety. Suitable for large amount of data, safety and performance requirements of high CSV application logic comma separated data storage engine Cluster / NDB.

BlackHole black engine, written in any data will disappear, generally used for recording binlog replication of the relay EXAMPLE storage engine is a don't do anything stub engine. It is designed as MySQL one example in the source code, used to demonstrate how to start writing a new storage engine. Similarly, it is of major interest to developers. EXAMPLE storage engine does not support indexing. In addition, Mysql storage engine interface definition of good. Interested developers can by reading the document prepared its own storage engine.

The index is a special file ( InnoDB data index is a table space is an integral part of ), they contain the data inside and outside all recorded reference pointer. The index is not a panacea, the index can speed up data retrieval operation, but can make the data modification operation slow. Each modified data recording, index must refresh time. In order to in certain procedures to remedy this one flaw, many SQL command has a DELAY_KEY_WRITE. This option is the role of temporary suppression of MySQL in the order of each insert a new record and each modified an existing immediately after the index on the index to refresh, refresh will wait until all record insert / modified after. The need to bring many new record is inserted into a data table of the occasion, the DELAY_KEY_WRITE option effects will be very obvious. In addition, the index will be in hard disk takes up considerable space. Therefore should only for the most frequent queries and most often sorted data column is indexed. Note that, if a data column contains many duplicate content, as it establishes index is not much actual effect.

From theoretic tell, can provide data and each of the fields were built an index, but MySQL the same data and index number is limited to 16.

1.InnoDB data table index

With InnoDB data table, in the InnoDB table, index on the InnoDB table importance is much greater. In InnoDB data table, the index will not only play a role in the search data records, or data row level locking mechanism, acenaphthene based. " The data row level locking" mean in transaction operation during the execution of the locking is being dealt with an individual record, do not allow other users to access. The lock will be affected ( but not

limited to ) SELECT, LOCKINSHAREMODE, SELECT, INSERT, UPDATE and FORUPDATE commands and DELETE command. For efficiency reasons, InnoDB data row level locking actually occur in their index, rather than the data itself. Obviously, the data row level locking mechanism only in relation to the data table having a suitable index for locking time to work.

2 limit

If the WHERE clause in the query terms are not equal ( WHERE coloum!= )MySQL , will not be able to use the index. Similarly, if the WHERE clause in the query terms used in function ( WHEREDAY ( column ) = MySQL ), will be unable to use the index. In the JOIN operation ( from multiple data extraction data ), MySQL only in the primary and foreign keys to the same data type to use index.

If the WHERE clause in the query conditions using comparison operators LIKE and REGEXP, MySQL only in search of template first character is not a wildcard conditions can use the index. For example, if the query is ' LIKE 'abc%, MySQL will use the index; if the query is ' LIKE %abc, ' MySQL will not use index.

In the operation of ORDERBY, MySQL only in the sorting condition is not a query condition expression condition that use index. ( even so, in a plurality of data query, even if the index is available, the index in accelerating ORDERBY has no effect). If a data column contains many duplicate values, even if it establishes index will not have a good effect. For example, if a data column contains the net is something such as" 0 / 1" or" Y / N" equivalent, there is no need for it to create an index.

Only when the database has enough test data, its performance test results have practical reference value. If the test database only hundreds of data recording, they are often in executing the first query command after being loaded into memory, it will make the subsequent inquiry command to perform very fast -- with or without using an index. Only when the records in a database of more than 1000, the amount of data is more than the amount of memory on the MySQL server, database performance testing results are meaningful. On the uncertainty in which data should create index on a column of the time, people from the EXPLAINSELECT command there can often get some help. This is simply to give a common SELECT command plus a EXPLAIN keyword as a prefix. With this key, MySQL will not to follow the SELECT command, but to analyze it. MySQL will be in the form of the query execution process and uses the index information list. In the output of the EXPLAIN command results, the first column is the data read from the database table name, they are to be read in the order. The type column specifies the data table and other table relationships ( JOIN ). In various types of relationships, efficiency is highest in system, followed by const,

eq_ref, ref, range, index and All ( All means: a data table corresponding to each record, this table all records must be read again -- this can often be used to an index to avoid ). Possible_keys data column gives the MySQL in search of the data record can be chosen each index. Key data column is MySQL practical selection index, this index in bytes of the key_len length in the columns of the data given in the. For example, for a INTEGER data column index, the byte length will be 4. If used in the composite index, the key_len data column can also see MySQL specific use of it which part. As a general rule, key_len data column value in the smaller is better. Ref data column gives the relationship of another data data select column name. Row data column is MySQL in executing this query is expected from this data and the read data line number. Row data column in all digital product can generally understand the need to deal with the number of combination query. Finally, the extra data column is provided with JOIN operation for more information about, for example, if the MySQL in executing this query must create a temporary table, will be listed in the extra see usingtemporary.

In the CHAR and VARCHAR data type column definition index, the index can be the length limit for a given number of characters ( this number must be less than the field the maximum allowed number of characters ). The benefit of this is can be generated in a relatively small size, the retrieval speed is fast compared to the index file. In most applications, the database string data mostly a variety of names, the index length is set to 10 ~ 15 characters were enough to narrow your search to a few data records. In the BLOB and TEXT data types to create index, to index length limits allowed by the MySQL; the maximum index full text index text field on the general index can only accelerate to appear in the field contents first string (i.e. field content retrieval operation initial characters ). If a field store is composed of several, or even more words constituting the larger text, general index of little use. This retrieval tends to form, the MySQL is very complex, if need to handle large volumes of data, response time will be very long.

Most of today's application in the heart is the underlying database. In this case, brook no delay in the design and implementation of the key business application data structure is very important.

All had good modeling tools, such as MySQL workbench support forward engineering, means that all use SQL code to create the database, and also can automatically write related objects and correct operation. This eliminates the developer or DBA error-prone and time-consuming process.

Data design and its response database version control and management of life cycle, such as the application, therefore, the most important is the data architect, database administrators, developers.

To understand their database and metadata design implementation of the appropriate change management needs. Link to certain information model driven method is optimal, but access to data modeling and metadata object manual method can be run.

In the change management, may face data management professionals are facing the most serious challenge is one of the existing physical database design in the successful implementation of these complex changes.

Fortunately, most good modeling tools, such as MySQL workbench can alleviate this problem, because they contain the synchronization efficiency, to allow the database administrator or developer to change physical data modeling, and then use the existing physical database to synchronize these changes. The tool is all about execution effect analysis or generation of the appropriate database code all the work, in the target database prior to implementation, easy to preview all changes.

In most of the tools, reverse engineering is also can be made very good - can modify a data modeling, to reflect on the existing physical database changes. This aspect is very important, because it is often required to perform an emergency change database, but if the change management or reverse engineering modeling, they need to perform the update to reflect the current IT infrastructure.

Application packaging / purchase for data transfer or application developers know in what form to use the underlying database often very difficult black box, in addition, the application package should be made to strengthen or other modifications, it is more important to understand the effect of these changes, and to ensure that they are right.

On the application management packs model driven method can greatly simplify the process. Modeling is the visualization of data and complex database structure definition of a perfect method. Through reverse engineering tool, very fast can be found in almost all good modeling tools, database management and developer or they can quickly visualize their application package database 's inner workings, and understand how to use the database. Should a need to modify the database or add operation, modeling tools can generate the analysis or generation code change.

Today's enterprises have very much for gripping or maintenance of data consumers. Some of them may be technical users, but may be many of them not, therefore, how to better education and communication ways to access data is a great challenge.

In addition, in the large-scale development team they used data structures are the same. They often need to understand how they in their own applications to coding, so that it is suitable to access the target database.

Again, the model for technical or non-technical personnel, it is a perfect way to understand how the data is to be defined? Or how to access? Like the MySQL workbench so good modeling tools can help them create modeling and export modeling pictures. Can also create web based or based on text report to convert large modeling into readable form report format.

MySQL

MySQL最初的开发者的意图是用mSQL和他们自己的快速低级例程(ISAM)去连接

表格。经过一些测试后，开发者得出结论：mSQL并没有他们需要的那么快和灵活。这导致了一个使用几乎和mSQL一样的API接口的用于他们的数据库的新的SQL接口的产生，这样，这个API被设计成允许为用于mSQL而写的第三方代码更容易移植到MySQL。

MySQL这个名字是怎么来的已经不清楚了。基本指南和大量的库和工具带有前缀“my”已经有10年以上，而且不管怎样，MySQL AB创始人之一Monty Widenius的女儿也叫My。这两个到底是哪一个给出了MySQL这个名字至今依然是个迷，包括开发者在内也不知道。

MySQL的海豚标志的名字叫“sakila”，它是由MySQL AB的创始人从用户在“海豚命名”的竞赛中建议的大量的名字表中选出的。获胜的名字是由来自非洲斯威士兰的开源软件开发者Ambrose Twebaze提供。根据Ambrose所说，Sakila来自一种叫SiSwati 的斯威士兰方言，也是在Ambrose的家乡乌干达附近的坦桑尼亚的Arusha的一个小镇的名字。

与其他的大型数据库例如Oracle、DB2、SQL Server等相比，MySQL自有它的不足之处，如规模小、功能有限（MySQL Cluster的功能和效率都相对比较差）等，但是这丝毫也没有减少它受欢迎的程度。对于一般的个人使用者和中小型企业来说，MySQL 提供的功能已经绰绰有余，而且由于MySQL是开放源码软件，因此可以大大降低总体拥有成本。

LAMP：

目前Internet上流行的网站构架方式是LAMP（Linux + Apache + MySQL + PHP / Perl / Python）和LNMP（Linux + Nginx + MySQL + php / perl / Python），即使用Linux 作为操作系统，Apache和Nginx作为Web服务器，MySQL作为数据库，PHP/Perl/Python 作为服务器端脚本解释器。由于这四个软件都是免费或开放源码软件（FLOSS)，因此使用这种方式不用花一分钱（除开人工成本）就可以建立起一个稳定、免费的网站系统。

MyISAMMysql的默认数据库，最为常用。拥有较高的插入，查询速度，但不支持事务InnoDB事务型数据库的首选引擎，支持ACID事务，支持行级锁定。BDB源自Berkeley DB，事务型数据库的另一种选择，支持COMMIT和ROLLBACK等其他事务特性Memory所有数据置于内存的存储引擎，拥有极高的插入，更新和查询效率。但是会占用和数据量成正比的内存空间。并且其内容会在Mysql重新启动时丢失。Merge将一定数量的MyISAM表联合而成一个整体，在超大规模数据存储时很有用。Archive非常适合存储大量的独立的，作为历史记录的数据。因为它们不经常被读取。Archive拥有高效的插入速度，但其对查询的支持相对较差。Federated将不同的Mysql服务器联合起来，逻辑上组成一个完整的数据库。非常适合分布式应用。Cluster / NDB高冗余的存储引擎，用多台数据机器联合提供服务以提高整体性能和安全性。适合数据量大，安全和性能要求高的应用。CSV逻辑上由逗号分割数据的存储引擎Cluster / NDB。

BlackHole黑洞引擎，写入的任何数据都会消失，一般用于记录binlog做复制的中继EXAMPLE存储引擎是一个不做任何事情的存根引擎。它的目的是作为MySQL源代码中的一个例子，用来演示如何开始编写一个新存储引擎。同样，它的主要兴趣是对开发者。EXAMPLE存储引擎不支持编索引。另外，Mysql的存储引擎接口定义良好。有兴趣的开发者可以通过阅读文档编写自己的存储引擎。

索引是一种特殊的文件（InnoDB数据表上的索引是表空间的一个组成部分），它们包含着对数据表里所有记录的引用指针。索引不是万能的，索引可以加快数据检索操作，但会使数据修改操作变慢。每修改数据记录，索引就必须刷新一次。为了在某种程序上弥补这一缺陷，许多SQL命令都有一个DELAY_KEY_WRITE项。这个选项的作用是暂时制止MySQL在该命令每插入一条新记录和每修改一条现有之后立刻对索引进行刷新，对索引的刷新将等到全部记录插入/修改完毕之后再进行。在需要把许多新记录插入某个数据表的场合，DELAY_KEY_WRITE选项的作用将非常明显。另外，索引还会在硬盘上占用相当大的空间。因此应该只为最经常查询和最经常排序的数据列建立索引。注意，如果某个数据列包含许多重复的内容，为它建立索引就没有太大的实际效果。

从理论上讲，完全可以为数据表里的每个字段分别建一个索引，但MySQL把同一个数据表里的索引总数限制为16个。

1．InnoDB数据表的索引

与InnoDB数据表相比，在InnoDB数据表上，索引对InnoDB数据表的重要性要大得多。在InnoDB数据表上，索引不仅会在搜索数据记录时发挥作用，还是数据行级锁定机制的苊、基础。“数据行级锁定”的意思是指在事务操作的执行过程中锁定正在被处理的个别记录，不让其他用户进行访问。这种锁定将影响到（但不限于）SELECT、LOCKINSHAREMODE、SELECT、FORUPDATE命令以及INSERT、UPDATE和DELETE 命令。出于效率方面的考虑，InnoDB数据表的数据行级锁定实际发生在它们的索引上，而不是数据表自身上。显然，数据行级锁定机制只有在有关的数据表有一个合适的索引可供锁定的时候才能发挥效力。

2．限制

如果WHERE子句的查询条件里有不等号( WHERE coloum!=)，MySQL将无法使用索引。类似地，如果WHERE子句的查询条件里使用了函数（WHEREDAY（column）=），MySQL也将无法使用索引。在JOIN操作中（需要从多个数据表提取数据时），MySQL 只有在主键和外键的数据类型相同时才能使用索引。

如果WHERE子句的查询条件里使用比较操作符LIKE和REGEXP，MySQL只有在搜索模板的第一个字符不是通配符的情况下才能使用索引。比如说，如果查询条件是LIKE'abc%'，MySQL将使用索引；如果查询条件是LIKE'%abc'，MySQL将不使用索引。

在ORDERBY操作中，MySQL只有在排序条件不是一个查询条件表达式的情况下才使用索引。（虽然如此，在涉及多个数据表查询里，即使有索引可用，那些索引在加

快ORDERBY方面也没什么作用）。如果某个数据列里包含许多重复的值，就算为它建立了索引也不会有很好的效果。比如说，如果某个数据列里包含的净是些诸如“0/1”或“Y/N”等值，就没有必要为它创建一个索引。

只有当数据库里已经有了足够多的测试数据时，它的性能测试结果才有实际参考价值。如果在测试数据库里只有几百条数据记录，它们往往在执行完第一条查询命令之后就被全部加载到内存里，这将使后续的查询命令都执行得非常快--不管有没有使用索引。只有当数据库里的记录超过了1000条数据总量也超过了MySQL服务器上的内存总量时，数据库的性能测试结果才有意义。在不确定应该在哪些数据列上创建索引的时候，人们从EXPLAINSELECT命令那里往往可以获得一些帮助。这其实只是简单地给一条普通的SELECT命令加一个EXPLAIN关键字作为前缀而已。有了这个关键字，MySQL 将不是去执行那条SELECT命令，而是去对它进行分析。MySQL将以表格的形式把查询的执行过程和用到的索引等信息列出来。在EXPLAIN命令的输出结果里，第1列是从数据库读取的数据表的名字，它们按被读取的先后顺序排列。type列指定了本数据表与其它数据表之间的关联关系（JOIN）。在各种类型的关联关系当中，效率最高的是system，然后依次是const、eq_ref、ref、range、index和All（All的意思是：对应于上一级数据表里的每一条记录，这个数据表里的所有记录都必须被读取一遍——这种情况往往可以用一索引来避免）。possible_keys 数据列给出了MySQL在搜索数据记录时可选用的各个索引。key数据列是MySQL实际选用的索引，这个索引按字节计算的长度在key_len数据列里给出。比如说，对于一个INTEGER数据列的索引，这个字节长度将是4。如果用到了复合索引，在key_len数据列里还可以看到MySQL具体使用了它的哪些部分。作为一般规律，key_len数据列里的值越小越好。Ref 数据列给出了关联关系中另一个数据表里的数据列的名字。row数据列是MySQL在执行这个查询时预计会从这个数据表里读出的数据行的个数。row数据列里的所有数字的乘积可以大致了解这个查询需要处理多少组合。最后，extra数据列提供了与JOIN操作有关的更多信息，比如说，如果MySQL在执行这个查询时必须创建一个临时数据表，就会在extra列看到usingtemporary字样。

在为CHAR和V ARCHAR类型的数据列定义索引时，可以把索引的长度限制为一个给定的字符个数（这个数字必须小于这个字段所允许的最大字符个数）。这么做的好处是可以生成一个尺寸比较小、检索速度却比较快的索引文件。在绝大多数应用里，数据库中的字符串数据大都以各种各样的名字为主，把索引的长度设置为10~15个字符已经足以把搜索范围缩小到很少的几条数据记录了。在为BLOB和TEXT类型的数据列创建索引时，必须对索引的长度做出限制；MySQL所允许的最大索引全文索引文本字段上的普通索引只能加快对出现在字段内容最前面的字符串（也就是字段内容开头的字符）进行检索操作。如果字段里存放的是由几个、甚至是多个单词构成的较大段文字，普通索引就没什么作用了。这种检索往往以的形式出现，这对MySQL来说很复杂，如

果需要处理的数据量很大，响应时间就会很长。

大部分当今应用的心脏就是底层数据库。在这种情况下，刻不容缓的设计和执行关键业务应用的数据结构是非常重要。

所有具有良好建模的工具，比如像MySQL workbench都支持正向工程，意味着所有使用的SQL代码能创建数据库，并也能自动书写相关的对象及正确运行。这个消除了开发人员或数据库管理员容易出错或耗时的过程。

数据设计及其响应的数据库有版本控制和生命周期管理，像应用程序一样，所以，最重要的就是数据架构师、数据库管理员、开发人员。

要了解为他们的数据库和元数据设计执行合适的变更管理需求。链接到某些信息库形式的模型驱动方法是最佳的，但获取数据建模和元数据对象的手动方法也是可以运行的。

在变更管理中，也许面对数据管理专业人员所面临最严峻挑战之一就是在已有的物理数据库设计中成功执行那些复杂的变化。

幸运的是，大部分良好建模工具，如MySQL workbench能缓解这类问题，因为它们包含同步效率，以允许数据库管理员或开发人员对物理数据建模进行更改，然后用已有的物理数据库来同步这些变化。该工具目前是对所有执行影响分析或生成合适的数据库代码的一切工作，在对目标数据库执行之前，容易预览所有的变更。

在大多数的工具中，逆向工程也是可以做得非常好的--可以修改一个数据建模，以反映对已有物理数据库做的变更。这一方面是非常重要的，因为往往需要对数据库执行紧急变更，但是如果对变更管理或逆向工程使用建模，他们需要执行更新以反映目前的IT基础设施。

应用程序包装/购买对于数据转移人员或应用开发人员了解以何种形式来使用底层数据库往往时非常困难的黑匣子，此外，对应用程序包应作出加强或其他修改，更重要的是要了解这些变化影响，并确保他们是正确的。

对应用程序管理包的模型驱动方法可以大大简化这一过程。建模是可视化了解数据关系和复杂数据库结构定义的一种非常完美的方法。通过逆向工程工具，很快可以发现几乎所有良好的建模工具，数据库管理与或开发者他们能快速地可视化他们应用程序包数据库的内部运作，并理解数据库是如何使用的。应需要作出对数据库进行修改或添加操作，建模工具能生成分析变更影响或生成代码。

当今企业有非常多的用于抓取或维护数据的消费者。其中一些人可能是技术型用户，但可能其中许多不是，因此，如何更好的教育与沟通方式来存取数据是一个巨大挑战。

此外，在大型开发团队中他们使用的数据结构都是一样的。他们经常需要了解他们如何在自己的应用中进行编码，以便它是合适的去访问目标数据库。

再次，模型对于技术或非技术人员而言，它是一种完美的方法来了解数据是如何进