1. 沙发数据库：
Apache CouchDB 是一个开源的面向文档的 NoSQL 数据库，它使用多种格式和协议来存储、传输和处理其数据，它使用 JSON 存储数据，使用 MapReduce 作为其查询语言的 JavaScript，以及用于 API 的 HTTP。它由 Apache 软件基金会开发，最初于 2005 年发布。它是用 Erlang 编写的。
2. MySQL：
MySQL 是一种基于结构化查询语言 (SQL) 的开源关系数据库管理系统 (RDBMS)。它由oracle 公司开发和管理，于1995 年5 月23 日首次发布。它被广泛应用于许多小型和大型工业应用程序，能够处理大量数据。
CouchDB 和 MySQL 的区别：
| S.NO. | CouchDB | MySQL | ||||||
|---|---|---|---|---|---|---|---|---|
| 1. | Developed by Apache Software Foundation and initially released in 2005. | Developed by Oracle and released on May 1995. | ||||||
| 2. | CouchDB is written in Erlang. | MySQL is written in C and C++. | ||||||
| 3. | The primary database model for CouchDB is Document Store. | The primary database model for MySQL is Relational DBMS. | ||||||
| 4. | In CouchDB there is no predefined datatypes. | MySQL have predefined datatypes such as float, date, number, etc. | ||||||
| 5. | CouchDB is Data Schema free. | In MySQL Data Schema is fixed. | ||||||
| 6. | CouchDB does not supports XML data format. | MySQL supports XML data format. | ||||||
| 7. | CouchDB supports Map Reduce method. | MySQL does not supports Map Reduce method. | ||||||
| 8. | CouchDB does not provides the concept of Referential Integrity. Hence, no Foreign Keys. | MySQL provides the concept of Referential Integrity and have Foreign keys. | ||||||
| 9. | CouchDB does not supports ACID transactions. | MySQL provides ACID transactions. | ||||||
| 10. | CouchDB provides Eventual Consistency method to ensure consistency in a distributed system. | MySQL provides Immediate Consistency method to ensure consistency in a distributed system. | 11. | Server operating systems for CouchDB are Android, BSD, Linux, OS X, Solaris and Windows. | Server operating systems for MySQL are FreeBSD, Linux, OS X, Solaris, Windows. | 12. | Famous companies like Akamai Technologies, Hothead Games, Inc., GenCorp Technologies, Vivint Solar, etc uses CouchDB. | Famous companies like Airbnb, Pinterest, Slack, Udemy, Twitter, etc uses MySQL. |