ER Model and Normalization

ER Model and Normalization

An ER model is a conceptual representation of the data and relationships in a database. It consists of entities, attributes, and relationships. Entities are the objects or things that are stored in the database, such as customers, products, or orders. Attributes are the properties or characteristics of entities, such as name, price, or quantity. Relationships are the associations or connections between entities, such as one-to-many, many-to-many, or one-to-one.

Normalization is a process of organizing the data in a database to reduce redundancy and improve integrity. It involves applying a set of rules or normal forms to decompose a table into smaller and simpler tables. The main benefits of normalization are:

- It eliminates anomalies, such as insertion, deletion, or update anomalies, that can cause inconsistency or loss of data.
- It reduces the storage space required by eliminating duplicate data.
- It enhances the performance of queries by simplifying the structure and reducing the number of joins.
- It facilitates the maintenance and modification of the database by minimizing the impact of changes.

There are several normal forms that can be applied to a table, such as first normal form (1NF), second normal form (2NF), third normal form (3NF), Boyce-Codd normal form (BCNF), fourth normal form (4NF), and fifth normal form (5NF). Each normal form has a specific condition that must be satisfied by a table. The higher the normal form, the more normalized the table is.

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