1. 微软 SQL 服务器：
Microsoft SQL Server 是一个关系数据库管理系统 (RDBMS)，它依赖于平台，并且是基于 GUI 和命令的软件。它支持企业 IT 环境中的各种事务处理、商业智能和分析应用程序。它由微软公司开发，最初于 1989 年 4 月 24 日发布。它是用 C 和 C++ 语言编写的。
2. 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。 MS SQL Server 和 CouchDB 的区别：
| S.NO. | MS SQL Server | CouchDB |
|---|---|---|
| 1. | Developed by Microsoft Corporation and initially released on April 24, 1989. | Developed by Apache Software Foundation and initially released in 2005. |
| 2. | MS SQL server is written in C and C++. | CouchDB is written in Erlang. |
| 3. | The primary database model for MS SQL Server is Relational Database. | The primary database model for CouchDB is Document Store. |
| 4. | The license for MS SQL Server is Commercial. | The license for CouchDB is open source. |
| 5. | In MS SQL Server Data Schema is fixed. | CouchDB is Data Schema free. |
| 6. | MS SQL Server supports XML data format. | CouchDB does not supports XML data format. |
| 7. | MS SQL Server have predefined datatypes such as float, date, number, etc. | In CouchDB there is no predefined datatypes. |
| 8. | MS SQL Server supports SQL. | CouchDB do not have SQL support. |
| 9. | MS SQL Server does not supports Map Reduce method. | CouchDB supports Map Reduce method. |
| 10. | MS SQL server supports Foreign Keys. | CouchDB does not supports Foreign Keys. |
| 11. | MS SQL server supports ACID transactions. | CouchDB does not supports ACID transactions. |
| 12. | MS SQL server provides Immediate Consistency method to ensure consistency in a distributed system. | CouchDB provides Eventual Consistency method to ensure consistency in a distributed system. |
| 13. | Server operating systems for MS SQL Server are Linux Windows. | Server operating systems for CouchDB are Android, BSD, Linux, OS X, Solaris and Windows. |
| 14. | Famous companies like Citi, Bank of America, UPS, etc uses MS SQL Server. | Famous companies like Akamai Technologies, Hothead Games, Inc., GenCorp Technologies, Vivint Solar, etc uses CouchDB. |