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所在平台: Udemy |
课程主页: https://www.udemy.com/course/er-to-relational-model/
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**课程名称：** 实体关系（ER）图到关系模式（Relational Schema） **课程概述：** 本课程将帮助您深入了解数据库设计的基本原理。您将学习如何从构建数据库的“蓝图”——实体关系（ER）图，将其转化为可以直接在关系型数据库管理系统（RDBMS）中实现的关系模式。 **您将学到：** * ER 图的基础知识 * 关系模型的基础知识 * ER 图到关系模型转换的重要性 * 具体的 ER 图到关系模型转换方法 **ER 图是什么？** ER 图是一种用于描述数据库结构的图示。它包含三个核心组成部分： * **实体（Entity）：** 现实世界中可识别的事物，如学生、书籍、汽车。 * **关系（Relationship）：** 实体之间的关联，例如“学生”和“课程”之间的“选课”关系。 * **属性（Attribute）：** 实体的性质或特征，如学生的姓名、学号、分数。 ER 图能清晰地展示数据元素以及它们之间的联系，为数据库的设计和最终实现提供了一个全面的视图。 **关系模型是什么？** 关系模型将数据库表示为一组“关系”（即表格），它描述了数据在数据库中的具体存储形式。 **为何需要 ER 图到关系模式的转换？** 在设计完数据库的 ER 图后，必须将其转换为关系模型，才能被 Oracle、MySQL 等 RDBMS 直接应用和实现。这个转换过程是将数据库的“草图”转化为可执行的“蓝图”。
INTRODUCTIONGreat Choice! Thank you for your interest in this course. Databases are a collection of organized information that can easily be accessed, managed and updated. A good database results in a better system. There are two steps to designing an effective database. First is making a rough skeleton of it (ER diagram) and conversion of the skeleton to a relational schema.WHAT YOU WILL LEARN?In this course you will learn:Basics of ER diagrams.Basics of Relational model.Importance of ER diagram to Relational model conversion.Conversion of ER diagram to relational model.WHAT IS ER DIAGRAM?An Entity-relationship model (ER model) describes the structure of a database with the help of a diagram, which is known as Entity Relationship Diagram. There are three main components of ER diagram Entity, Relationship and attributes.An entity can be a real-world object, either animate or inanimate, that can be easily identifiable. For example: Student, Book, CarThe association among entities is called a relationship. For example, students enroll in a course. Here enroll is a relationship between entities Student and Course.Entities are represented by means of their properties, called attributes.For example, Name, Roll No, Marks are attributes of entity Student.ER diagram gives us an idea of how the final system will look like after its complete implementation. It defines the data elements and the relationships between the data elements. ER diagrams are used to show how data is stored, connected, accessed and updated in the database management system.WHAT IS RELATIONAL MODELRelational Model (RM) represents the database as a collection of relations. Relational Model represents how data is stored in a database in the form of a table.NEED OF CONVERSION OF ER DIAGRAM TO RELATIONAL SCHEMAAfter designing the ER diagram of the system, we need to convert it to Relational models which can directly be implemented by any RDBMS like Oracle, MySQL etc. Rough skeleton of any database needs to be converted into relational form to make use of it.
