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What is the relationship between ERI and relational database?
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DER or Entity-Relationship Diagram, as its name says, is a graphical representation of the entities needed in a data model and their relationships, therefore it is an abstract form.
Relational databases are the mechanisms that embody these representations and produce a database with these entities and have facilities that allow them to be accessed in a related way.
Precisely because both are based on the data relationship they fit well.
It is common to say that the ERI is used to create a logical model and the database is the physical model. It’s a little more complicated than that, but it’s a simplified way of understanding.
The database is the implementation of what has been specified in der.
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A relationship model entity (MER) describes the objects (entities) involved in a business domain, with their characteristics (attributes) and how they relate to each other (relationships). This conceptual model is represented graphically by the relationship entity diagram (ER or DER). This diagram facilitates communication between team members, as it offers a common language used both by the analyst, responsible for raising the requirements, and the developers, responsible for implementing what was modeled.
Already one relational database models the data in a way that they are perceived by the user as tables, or more formally relations. The standard language of Relational Databases is Structured Query Language, or simply SQL, as it is best known.
The relationship between ERI and relational databases is that an ER model is usually implemented as a database. In the case of a relational database, which stores data in tables, the tables themselves represent the entities. Some data fields in these tables point to indexes in other tables, which represent relationships.
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The DER is the diagram of entities and relationships or you will show the part of it as the entities(tables) of your database are related would be a logical way to represent this relationship, and the relational database a physical form.
Generally in the ERI you put several entities relating, for example product table with the supplier, product may have only one supplier and the supplier various things, the relational model is the same thing, but with its direct application in the database already, through primary and foreign keys.
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