2. Relational database (relational Database,rdb)

A database based on a relational model.

A relational database is a collection of data and database objects.

Overview: consists of an association between a data table and a data table. A data table is a two-dimensional table that typically consists of rows and columns, each of which describes a particular aspect or part of an object in the database and its properties. A row in a data table represents a record and an object that represents one of many objects with the same properties; a column in a data table is often called a column or property, representing properties that are common to stored objects in the corresponding data table.

Relationship is a normalized two-dimensional table with the following characteristics:

• Attribute values are atomic and cannot be decomposed.
• No duplicate rows
• Theoretically there is no line order, but sometimes it can be used in a row order

2. Relational database (relational Database,rdb)