1. 甲骨文：
Oracle 是一家总部位于美国加利福尼亚州的美国跨国计算机技术公司，由 Larry Ellison Bob Oates 于 1977 年创立。Oracle 是一个关系管理系统。它是第一个专为网格计算设计的数据库，它提供了最灵活和最具成本效益的方式来管理信息和应用程序。它运行一个主要平台，如 WINDOW、UNIX、LINUX 和 MACOS。它将关系数据库中的数据由用户通过称为 SQL 的应用程序或查询语言访问。
这是oracle的不同版本：
- 企业版
- 标准版
- 速成版
- 甲骨文版
2. PostgreSQL :
PostgreSQL 是一个关系数据库管理系统。它是一个开源数据库，活跃开发了 20 多年。它支持 RDBMS 提供开放连接的所有特性，可在 UNIX、MACOS、WINDOW、LINUX 等主要平台上运行。 它还支持各种编程语言 C、C++、 Java、PYTHON、PERL 等的视频文本音频图像编程接口。它也称为 POSTGRES。
Oracle 和 PostgreSQL 的区别：
| Basis of | Oracle | PostgreSQL |
|---|---|---|
| Definition | Oracle is a relational management system.It is first database designed for grid computing. | PostgreSQL is free open source relational-database management system emphasizing extensibility and SQL compliance. |
| Development | Oracle developed by Larry Ellison and Bob in 16 june 1977. | PostgreSQL developed by PostgreSQL global Development group in 8 july 1996. |
| Written in | Oracle written in c and C++ language. | PostgreSQL written in C language. |
| Latest version | Oracle runs on 19c version which release on February 2019. | PostgreSQL runs on PostgreSQL 12.3 version which release on may 2020. |
| License | Oracle required license. | PostgreSQL is open source. |
| Support | Oracle support cost based. | PostgreSQL provide free support or option with paid support at low cost. |
| Security | Oracle is more secure than PostgreSQL. | PostgreSQL provide good security but it is not secure as Oracle. |
| Programming language | Oracle support various language like C, C++, JAVA, PERL, .NET, JAVA SCRIPT, PHP etc. | PostgreSQL support C, C++, JAVA, PERL, SCALA, PHP, C#, COBOL, JAVA SCRIPT etc. |
| Features. | Availability. Fast-Start Failover to Standby Database. Business Intelligence. SQL Support for Analytic Applications. Clustering. Real Application Clusters (RAC) Performance. Content Management. Database Overall. Database Security. Grid Computing. |
Complex SQL queries. SQL Sub-selects. Foreign keys. Trigger. Views. Transactions. Multi version concurrency control (MVCC) |