这篇关于SQL 和 NoSQL(SQL and NoSQL)比较的文章将阐明关于各自优势和局限性的辩论。自从 NoSQL 数据库的嗡嗡声在(NoSQL)将数据存储到NoSQL数据库中发展起来后，我就想探索这两个概念以深入了解它。我花了一些时间才弄清楚真正导致NoSQL数据库发展的东西。
好吧，这一切都归结为以快速、真实和连接的方式为最终用户提供最佳体验的追求。随着存储部门的技术发生巨大变化，数据库开发人员正在尝试优化事物以产生更好的性能。
SQL 和 NoSQL 数据库的基础知识：
什么是 SQL 数据库
说到SQL数据库，基本概念是这样的；它有一个关系数据库(Relational database)。是的！SQL数据库是关系数据库。那么究竟什么是关系数据库呢？关系数据库严格使用关系（通常称为表）来存储数据。关系数据库通过使用在数据集中找到的共同特征来匹配数据。生成的组称为Schema。
关系数据库中的关系（表）被划分为一组行和列。元组代表使用查询检索的数据库表中的一行。
那么 SQL 有什么帮助呢？
SQL（结构化查询语言(Structured Query Language)）是一种编程语言，用于管理关系数据库中的数据。Microsoft SQL Server就是最好的例子。Microsoft SQL Server是一种关系数据库，用于存储和检索同一计算机上或网络上的应用程序的数据。
SQL Server 的基本特性
- 关系数据库是一组包含适合预定义类别的数据的表。
- 每个表在列中包含一个或多个数据类别。
- 每行包含由列定义的类别的唯一数据实例。
- 用户可以在不知道数据库表结构的情况下访问数据库中的数据。
SQL 数据库的限制
可扩展性(Scalability)：用户必须在昂贵且难以处理的强大服务器上扩展关系数据库。要扩展关系数据库，它必须分布在多个服务器上。跨不同服务器处理表是混乱的。
复杂性(Complexity)：无论如何，在SQL Server 中，数据必须适合表格。如果您的数据不适合表格，那么您需要设计复杂且难以处理的数据库结构。
什么是 NoSQL 数据库？
在过去的几年里，“一刀切”——关于数据存储的思考一直受到科学(Science)和网络公司的质疑，这必然导致各种各样的替代数据库的出现。移动以及新的数据存储通常包含在NoSQL一词中。
NoSQL的基本质量是它可能不需要固定的表模式，通常避免连接操作，并且通常水平扩展。学术(Academic)研究人员通常将这些数据库称为结构化存储，该术语将经典关系数据库作为一个子集。
NoSQL数据库还权衡了“ACID”（原子性、一致性、隔离性和持久性）。NoSQL数据库在不同程度上甚至允许数据架构因记录而异。如果NoSQL(NoSQL)中不存在模式或表，那么如何可视化数据库结构？好吧(Well)，这就是答案
无需架构(No schema required)：无需先定义严格的数据库架构，即可将数据插入NoSQL数据库。(NoSQL)因此，可以随时更改插入数据的格式，而不会中断应用程序。这提供了巨大的应用程序灵活性，最终提供了巨大的业务灵活性。
自动弹性：(Auto elasticity: )NoSQL自动将您的数据分散到多个服务器上，无需应用程序协助。可以从数据层添加或删除服务器，而无需应用程序停机。
集成缓存：(Integrated caching:)为了增加数据并提高性能，NoSQL技术将数据缓存在系统内存中。这与必须使用单独的基础架构完成的SQL数据库形成对比。
描述NoSQL中数据存储的架构，有三种流行的NoSQL数据库。
- 键值存储(Key-value stores)。顾名思义，键值存储是一个存储索引值以通过键检索的系统。这些系统可以保存结构化或非结构化数据。
- 面向列的数据库(Column-oriented databases)。与关系数据库的情况不同，面向列的数据库包含一个可扩展的密切相关数据列，而不是将信息集存储在高度结构化的列和行表中，每个记录具有统一大小的字段。
- 基于文档的商店(Document-based stores)。这些数据库将数据存储和组织为文档集合，而不是作为每个记录具有统一大小字段的结构化表格。使用这些数据库，用户可以在文档中添加任意数量、任意长度的字段。
这张图显示了他们三个之间的区别。
NoSQL数据库的优势
1) NoSQL 数据库通常比关系数据库更快地处理数据。
2) NoSQL 数据库通常也更快，因为它们的数据模型更简单。
3) 主要的 NoSQL(Major NoSQL)系统足够灵活，可以更好地使开发人员能够以满足其需求的方式使用应用程序。
SQL NoSQL 比较(SQL NoSQL Comparision)与结论(Conclusion)：
随着时间的推移， SQL(SQL)和NoSQL一直是伟大的发明，以保持数据存储和检索的优化和流畅。批评其中任何一个都无济于事。如果现在NoSQL很流行，那并不意味着它是满足您所有需求的灵丹妙药。这两种技术在他们所做的事情上都是最好的。开发人员可以根据情况和需要更好地利用它们。
如果您想探索NoSQL，可以下载Microsoft NoSQL Azure白皮书。
如果您想了解MySQL 和 SQL Server 之间的区别，(difference between MySQL and SQL Server)请访问此处。(Go here if you want to learn about the difference between MySQL and SQL Server.)
Difference between SQL and NoSQL: A Comparison
This artiсle on SQL and NoSQL comparison will throw light on the debate on advantages and limitations on each. Ever since the buzz of NoSQL database evolved in storing data into the NoSQL databases, I thought of exploring both the concepts to reach out to its depth. And it took me some time to figure out things that actually lead to the evolution of the NoSQL database.
Well, it all comes down to the quest of providing the best possible experience to the end-users in a quick, real and connected way. Database developers are trying to optimize things to yield better performance as the technology in the storage department is changing drastically.
Basics of SQL and NoSQL database:
What is SQL database
Talking about SQL database, the basic concept is that; it has is a Relational database. Yes! SQL database is a relational database. So what exactly is a relational database? A relational database strictly uses relations (frequently called as tables) to store data. A relational database matches data by using common characteristics found in the dataset. And the resulting group is termed as Schema.
A relation (table) in a relational database is divided into a set of rows and columns. A Tuple stands for a row in a database table that is retrieved using a query.
So how does SQL help?
SQL (Structured Query Language) is a programming language that is used to manage data in relational databases. Microsoft SQL Server is the best example. Microsoft SQL Server is a relational database that is used to store and retrieve data by applications either on the same computers or over the network.
Basic features of SQL server
- A relational database is a set of tables containing data fitted into predefined categories.
- Each table contains one or more data categories in columns.
- Each row contains a unique instance of data for the categories defined by the columns.
- The user can access data from the database without knowing the structure of the database table.
Limitations for SQL database
Scalability: Users have to scale relational databases on powerful servers that are expensive and difficult to handle. To scale a relational database it has to be distributed on multiple servers. Handling tables across different servers is chaos.
Complexity: In SQL server’s data has to fit into tables anyhow. If your data doesn’t fit into tables, then you need to design your database structure that will be complex and again difficult to handle.
What is NoSQL database?
In the past few years, the ”one size fits all“ – thinking concerning data stores has been questioned by both, Science and web companies, which has to lead to the emergence of a great variety of alternative databases. The movement as well as the new datastores are commonly subsumed under the term NoSQL.
The basic quality of NoSQL is that it may not require fixed table schemas, usually avoid join operations, and typically scale horizontally. Academic researchers typically refer to these databases as structured storage, a term that includes classic relational databases as a subset.
NoSQL database also trades off “ACID” (atomicity, consistency, isolation, and durability). NoSQL databases, to varying degrees, even allow for the schema of data to differ from record to record. If there doesn’t exist schema or a table in NoSQL, then how do you visualize the database structure? Well here is the answer
No schema required: Data can be inserted in a NoSQL database without first defining a rigid database schema. As a corollary, the format of the data being inserted can be changed at any time, without application disruption. This provides immense application flexibility, which ultimately delivers substantial business flexibility.
Auto elasticity: NoSQL automatically spreads your data onto multiple servers without requiring application assistance. Servers can be added or removed from the data layer without application downtime.
Integrated caching: In order to increase data through and increase performance advance NoSQL techniques cache data in system memory. This is in contrast to SQL database where this has to be done using the separate infrastructure.
Describing the architecture of data storage in NoSQL, there are three types of popular NoSQL databases.
- Key-value stores. As the name implies, a key-value store is a system that stores values indexed for retrieval by keys. These systems can hold structured or unstructured data.
- Column-oriented databases. Rather than store sets of information in a heavily structured table of columns and rows with uniform-sized fields for each record, as is the case with relational databases, column-oriented databases contain one extendable column of closely related data.
- Document-based stores. These databases store and organize data as collections of documents, rather than as structured tables with uniform-sized fields for each record. With these databases, users can add any number of fields of any length to a document.
The image shows the difference between three of them.
Advantages of NoSQL database
1) NoSQL databases generally process data faster than relational databases.
2) NoSQL databases are also often faster because their data models are simpler.
3) Major NoSQL systems are flexible enough to better enable developers to use the applications in ways that meet their needs.
SQL NoSQL Comparision and Conclusion:
SQL and NoSQL have been great inventions over time in order to keep data storage and retrieval optimized and smooth. Criticizing any one of them will not help the cause. If there is a buzz of NoSQL these days, it doesn’t mean it is a silver bullet to all your needs. Both technologies are best in what they do. It is up to a developer to make better use of them depending on the situation and needs.
If you are looking to explore NoSQL, you can download Microsoft NoSQL Azure whitepaper.
Go here if you want to learn about the difference between MySQL and SQL Server.
