Of the three components of a relational database model, the one that is not included is the data store.

Of the three components of a relational database model, the one that is usually not included is the data store.

The data store is the physical structure that actually stores the data in a relational database, and it involves how the data is stored on disk and how it is accessed. The three components of a relational database model typically include: a relational data structure, a collection of relational operations, and relational integrity constraints.

The relational data structure, which is the foundation of a relational database, is a two-dimensional table that consists of rows and columns. Each row represents a record and each column represents an attribute. Each attribute in a relational data structure has a name and a corresponding data type.

The set of relational operations is the various operations that can be performed in a relational database. These operations typically include inserts, deletes, updates, and queries. Relational operation collections are important for maintaining the integrity, security, and performance of a relational database.

Relational integrity constraints are rules used in relational databases to ensure data integrity. These rules include primary key constraints, foreign key constraints, uniqueness constraints, and check constraints. Relational integrity constraints ensure data accuracy and consistency.

Applications of relational database model:

1. Enterprise management: relational database model can be used for all kinds of data storage and query in enterprise management. For example, an enterprise can use a relational database to store employee information, customer information, product information, etc., and categorize, index and query them. The relational database model can also be used to manage the business data of an enterprise, such as sales orders, inventory, and so on. With the relational database model, companies can better organize and manage data and improve work efficiency.

2, e-commerce: relational database model is also widely used in e-commerce. E-commerce websites usually need to store user information, shopping cart data, order data, etc., and make real-time inquiries and processing. Relational databases can provide efficient data storage and query functions to support e-commerce site's rapid response and flexible business logic.

3, information systems: relational database model can be used for a variety of information systems for data storage and query. For example, the student information management system can use a relational database to store student information, performance information, etc., to facilitate the administrator to query and manage. Relational database model can also be used to manage library book information, borrowing status, etc.. Through the relational database model, the information system can better organize and manage data to improve data processing efficiency and accuracy.