Relational and structured databases, database structuring

Relational and structured databases, database structuring
Relational

What is a relational database? The foundation of relational databases is the relational model proposed in 1970. This model consists of three parts: relational data structure, relational operation set, and Relational integrity constraint.

Relational Data Structure

I understand that it is an object link Model, which was proposed in 1976 as a two-dimensional table Model. Generally, ergraphs are used for modeling.

Relational Database Service

It is a data organization composed of two tables and their relationships.

Structured Data

Structured data can be represented in the tables Table. On the contrary, text, images, videos, XML, and HTML are not structured data.

Structured Query speech

Structured Query Language is SQL. It was a relational database language born in 1974. That is to say, it exists only when it comes to relational databases.

My understanding:
1. If the dataset is relational, the data must be structured.
2. if the data is structured, the data set may be relational.
3. Relational databases must be data sets (databases). Only one table of data cannot form a one-to-many relationship.
4. The structure must be an exponential data, that is, whether the data has formed a two-dimensional table.
5. Relational databases can store unstructured data, but only one field can be used for storage, instead of a table.

This article is from the csdn blog of ouyida3.
2015.3.26