参考的数据库文档主要有:目前国内的常见的PHP系统的数据库
作者:杨鑫奇
最近手头上有3个项目开动,其他2个都是从底层开始的,一个已经开始了一段时间的了,在小城市小团队开发的条件下,都没有专门的DBA来做数据库的设计和维护,往往都是开发人员顶上,可是看了很多的数据库的设计,感觉很多设计都不是很完美,包括DZ的Ucenter和UcenterHome的数据库,所以这段时间话了近5个小时的时间好好的整理了下数据库方面的基本内容,配合现有的框架来实现快捷的数据库设计,来满足目前项目的需求
参考的数据库文档主要有:目前国内的常见的PHP系统的数据库
DZ6.0的数据库 ECSHOP SUPESITE7 UCHOME UCENTER的数据库结构 还有DEDECMS的数据库结构,这些都是来自 PHPCHINA论坛,有需要的朋友可以联系我或者留下邮件我发送过去,今天在读这些范式,设计注意事项的文章中,就想到了大学时候的数据库课程,记得大一的时候,涛涛就拉我一起去听比听03届的数据库课程,感觉那个时候听的也比较入神,感觉老师也讲的好,后来就到了我们自己上数据库课程的时候,来的老师感觉就会讲PPT,根本没有设计经验的刚刚毕业的研究生来教我们的,嘎嘎,那个时候就不想去上课的了,一点学习的冲动都没有了,老师自己教的累,我们学的也累,现在想想大学时候真的没有把基础打好,现在要来恶补一下了。鄙视下自己的大学时候的生活和心态,没有好好的学好好专业课,呵呵,书动用时方恨少.......
入题:
数据库设计方面我主要分为如下:
一、设计工具
因为现在只做LNMP(Linux + Nginx +PHP +MySQL)方面的开发了,所以数据库设计上我就选了数据库的设计工具了,现在用的是MYSQL自己的 开发的工具:MySQL Workbench 5.2.16 OOS Beta 设计的开发版本,这个方面主要是针对MYSQL的数据库开发的,从5.2的各个版本一直在用,发现不少bug但是对于现在的设计还是很有用的,BUG还是很多,有待完善,主要的特点终于 a,只做MySQL比较专业 b,可以反向数据库 c,可以管理和监控MySQL d,界面上和SQLSERVER MANAGER差不多,还是用起来比较顺手的,好了上张图
二、数据库设计的注意实现及基础知识复习
这些直接上图了
大家可以下载下来看,太大了

InnoDB uses redologs and undologs to ensure data consistency and reliability. 1.redologs record data page modification to ensure crash recovery and transaction persistence. 2.undologs records the original data value and supports transaction rollback and MVCC.

Key metrics for EXPLAIN commands include type, key, rows, and Extra. 1) The type reflects the access type of the query. The higher the value, the higher the efficiency, such as const is better than ALL. 2) The key displays the index used, and NULL indicates no index. 3) rows estimates the number of scanned rows, affecting query performance. 4) Extra provides additional information, such as Usingfilesort prompts that it needs to be optimized.

Usingtemporary indicates that the need to create temporary tables in MySQL queries, which are commonly found in ORDERBY using DISTINCT, GROUPBY, or non-indexed columns. You can avoid the occurrence of indexes and rewrite queries and improve query performance. Specifically, when Usingtemporary appears in EXPLAIN output, it means that MySQL needs to create temporary tables to handle queries. This usually occurs when: 1) deduplication or grouping when using DISTINCT or GROUPBY; 2) sort when ORDERBY contains non-index columns; 3) use complex subquery or join operations. Optimization methods include: 1) ORDERBY and GROUPB

MySQL/InnoDB supports four transaction isolation levels: ReadUncommitted, ReadCommitted, RepeatableRead and Serializable. 1.ReadUncommitted allows reading of uncommitted data, which may cause dirty reading. 2. ReadCommitted avoids dirty reading, but non-repeatable reading may occur. 3.RepeatableRead is the default level, avoiding dirty reading and non-repeatable reading, but phantom reading may occur. 4. Serializable avoids all concurrency problems but reduces concurrency. Choosing the appropriate isolation level requires balancing data consistency and performance requirements.

MySQL is suitable for web applications and content management systems and is popular for its open source, high performance and ease of use. 1) Compared with PostgreSQL, MySQL performs better in simple queries and high concurrent read operations. 2) Compared with Oracle, MySQL is more popular among small and medium-sized enterprises because of its open source and low cost. 3) Compared with Microsoft SQL Server, MySQL is more suitable for cross-platform applications. 4) Unlike MongoDB, MySQL is more suitable for structured data and transaction processing.

MySQL index cardinality has a significant impact on query performance: 1. High cardinality index can more effectively narrow the data range and improve query efficiency; 2. Low cardinality index may lead to full table scanning and reduce query performance; 3. In joint index, high cardinality sequences should be placed in front to optimize query.

The MySQL learning path includes basic knowledge, core concepts, usage examples, and optimization techniques. 1) Understand basic concepts such as tables, rows, columns, and SQL queries. 2) Learn the definition, working principles and advantages of MySQL. 3) Master basic CRUD operations and advanced usage, such as indexes and stored procedures. 4) Familiar with common error debugging and performance optimization suggestions, such as rational use of indexes and optimization queries. Through these steps, you will have a full grasp of the use and optimization of MySQL.

MySQL's real-world applications include basic database design and complex query optimization. 1) Basic usage: used to store and manage user data, such as inserting, querying, updating and deleting user information. 2) Advanced usage: Handle complex business logic, such as order and inventory management of e-commerce platforms. 3) Performance optimization: Improve performance by rationally using indexes, partition tables and query caches.


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