What is ER Diagram?

The entity Relationship Diagram is a type of diagram which demonstrates the relationship of the entity in a database. We explain the logical structure of the database using this diagram. This diagram is created using entities, attributes, and relationships. What is ER Model? ER Model is a concept that is used to produce a well-designed database where we represent real-world entities and their relationships. You will implement polyglot persistence using one Relational Database assignment help in Database Management Systems (RDBMS) and one NoSQL database. You will use Python to perform the four essential CRUD functions of persistent storage (Create, Read, Update and Delete). The NoSql database can be either a key-value database, document database, or graph database.

Why use ER Diagrams?

It provides a preview of tables, relationships among tables, and constraints. It provides the logical structure of the database. Components of an ERD? It has three components.

  • Entities
  • Attributes
  • Relationships

Entity: An entity is a thing for which we can store data in the database. In ER Diagram Entities in DBMS assignment help are represented as rectangles. An entity is also of two types a strong entity and a weak entity. A strong entity has a unique key and does not depend on other entities on the other hand weak entity depends on a strong entity’s primary key to get uniquely identified. Attributes: The property of an entity is called an attribute. There are several different types of attributes:  Simple: which cannot be further split into other attributes. Composite: That can be split into other attributes. Derived: That is calculated from another attribute. Single-value: An attribute that has only one value. Multi-Value: An attribute that has more than one value. Relationship It is an association among entities.

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What is Cardinality?

Cardinality represents numerical attributes of the relationship between two entities.

Types of cardinal relationships:

  • One-to-One Relationships
  • One-to-Many Relationships
  • May to One Relationships
  • Many-to-Many Relationships

One-to-One Relationships: One attribute from an entity is associated with at most one attribute of another entity and vice versa. One-to-Many Relationships: One attribute from an entity is associated with multiple attributes of another entity for database management assignment help services. May to One Relationship: More than one attribute from an entity is associated with at most one attribute of another entity. Many-to-Many Relationships: One attribute from an entity is associated with more than one attribute of another entity and vice versa. There are a few different methods to draw ER Diagrams. Chen Notation.

Example of Database

1- For the RDBMS (SQLite3) element, using the normalized database design – defined in section(2) – implement a minimum of four tables. Use Python. You need to implement a minimum of four tables. At least one of the tables should be a “link table”. Example of tables: (Vehicle, customer, rental booking, employee) 2- For the RDBMS (SQLite3) element, use Python to perform the four essential CRUD functions of persistent storage (Create, Read, Update and Delete). 3-For the NoSQL element, use Python to perform the CRUD functions. 4-For polyglot persistence, use Python to implement the use case. Note: Both the relational and the NoSQL database should be populated with relevant and sufficient data, allowing for a comprehensive assessment of the use case for the car rental company. In this context, 4-5 records may be considered “too few”, and 100s of records are far “too many”

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