关系数据库采用的数据结构是什么？

单一数据结构-关系（表文件）。
A relational database table uses a two-dimensional table to store data. It is a logical group with related information arranged in rows and columns.它类似于 Excel 工作表。
A database can contain any number of data tables. From the user's perspective, the logical structure of a relational model is a two-dimensional table consisting of rows and columns. This two-dimensional table is called a relationship. In layman's terms, a relationship is equivalent to a table. Advanced data relational databases store data in a structured manner. Each data table needs to define each field (that is, define the table structure first), and then store the data according to the table structure. This has the advantage that the form and content of the data have been defined before the data is stored, so the reliability and stability of the entire data table is relatively high. But the problem is that after the data is saved, it will be very difficult to change the structure of the data table. In order to avoid duplicates, standardize data and make full use of storage space, relational databases store data in the form of a minimal relational table, so that data management can be very clear and obvious at a glance. Of course, this is mainly the case with a data table. The situation is different if there are several tables. Because the data is multiple data tables, there are complex relationships between the data tables. As the number of data tables increases, data management becomes more complex. Reference Source: Baidu Encyclopedia – Relational Database Reference Source: Baidu Encyclopedia – Relational Database

怎样查看一个数据库里面的所有表？怎样查看表的结构和变量属性？

oracle 查看表结构，表里的数据

1 、首先我们打开PLSQL工具，连接需要比对的ORACLE数据库。
2 . 登录后，单击“工具”并选择“比较用户对象”。
我们首先匹配数据表结构，避免数据匹配时无法更改数据的风险。
3 、在弹出的界面中选择我们需要匹配的数据表，点击目标会话（targetsession），输入需要匹配数据对应的数据库用户名和密码，点击确定，连接成功后点击匹配数据（Compare）。
4 、如果数据表结构有差异，弹出界面会显示数据库中表结构的差异，并形成相关更新SQL语句。
数据表匹配仅考虑源数据库中不存在的表或列。
检查SQL语句是否是我们想要匹配的。
点击确认匹配，数据库表结构匹配完成。
5 . 登录成功后，点击“工具”，选择“比较表数据”。
6 . 单击“确认匹配”，数据库表数据匹配完成。

数据库表结构设计

1 . The basic overview table of representative geological sites includes geographical location, park scope, natural conditions, etc. (Table 6 -2 ).表6 -2 基本概况（JBGK.MDB）数据库结构表数据项说明： 地质公园编号：国家代码前3 位，按行政区划代码（GB/T2 2 6 0-9 8 ）填写，后3 位为地质遗迹点序号。
如果公园规模较大、跨境，则按照主要景区所在区域进行编号，最后六位数字为序号，保证地质遗迹编号的唯一性。
地质遗迹分类：为适应现阶段地质遗迹调查、地质公园建设与发展规划、科学普及的需要，赵挺（2 009 ）基于系统地球科学理论，提出了明确的地质遗迹概念，构建了专题分类体系。
以此为基础，他完成了中国国家地质公园地质遗迹的分类。
2 、景区及景区数据（表6 -3 、表6 -4 ） 表6 -3 景区表结构（JQ.MDB）表 表6 -4 景区表结构（JD.MDB）表 景区与景区数据关系（表6 -5 ）为一对多关系。
That is, a scenic spot has more than one scenic spot, and every scenic spot can only belong to a specific scenic spot.