Data Model Relationships 101: Simplified Guide for Beginners


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Data and its usage are becoming increasingly important in today’s data-driven world. Data Model Relationships have become an essential factor in managing data. In simple terms, Data Modeling is “the process of creating a data model.” Building a sound Data Management System requires several right technological, architectural, and design decisions. You must ensure that the data’s architecture and structure match the technology you’ve selected and effectively solve all of your business objectives.

Every contemporary Data-Driven Organization creates massive amounts of data. Due to differences in business activities, systems, and procedures, data must be appropriately consolidated, cleaned, and transformed to allow meaningful analytics. A Data Modeling effort is required to structure the data consistently and store it in a usable way for multiple reasons.

In this Data Model Relationships guide, we discuss the importance of Data Model Relationships, their types, and the many relationships that you can create while building your own Data Model. We’ll also go over why Data Integrity and Normalization are so important to include in your Data Model Relationships.

Table of Contents

What is Data Modeling?

Data Modeling Overview: Data Model Relationships | Hevo Data
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Data Modeling is the process of creating visual representations of data to express data and its relationships. It is a concise display of information systems, their requirements, and their capabilities, using a whole set of screens, reports, and processes needed to capture, update, retrieve, and delete the data. A Data Model Relationship specifies the database what sort of data will be held and how it will be organized.

For businesses, creating Data Model Relationships is an extensive activity, since not only should it help to map information and their relationships, but it must also meet all business requirements for better understanding and analysis. A Data Model Relationship should also be stable in the face of changes in requirements, and flexible to accommodate new requirements with minimal impact on the existing structure.

Why is Data Modeling Important?

Data Modeling is a crucial component of the design process that ensures the efficacy of your data platform. Data Models visualize and express data for storage, retrieval, and analysis.  They use diagrams, symbols, or text to represent data and its relationships. 

A Data Model determines where to collect and store data and the quantity of data to be extracted from different Data Entities. It is also essential to understand the Data Model Relationships that connect these entities.

Data Modeling’s ultimate goal is to develop clear data standards for the entire company. For instance, a Data Model for an eCommerce website can outline the client data you’ll collect. It will specify how that data should be labeled and its relationship to product information and sales. The use of charts, characters, and textual references to illustrate the way Data Flows through a Software Program or the Data Architecture inside an enterprise is common while “modeling” these numerous systems and processes.

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Three Levels of Data Modeling

Data Modeling occurs at three levels: Physical, Conceptual, and Logical. They help align your Data Project’s why, how, and what.

  • A Physical Model is a framework explaining how data gets physically stored in a database.
  • A Logical Model separates the physical and conceptual levels and develops a technical map of rules and data structures that can be implemented in databases. 

Physical Data Model

The Physical Data Model specifies the types of data you’ll store and technical data requirements. Database Analysts and Developers use it to create databases and related data structures.

Data type definitions tell whether a piece of data is an integer or float. Technical requirements consist of metrics like storage demands, access speed, data redundancy, storing a particular amount of data in numerous locations to maximize durability, query performance, and so on.

Physical Data Model: Data Model Relationships | Hevo Data
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Conceptual Data Model

Without getting into technical specifics, Conceptual Data Models illustrate the concepts and principles that govern the business processes you’re modeling. This Data Model Representation aligns Business Stakeholders, System Architects, and Developers on the same project and business requirements, such as what data the data system contains, how elements should relate to one another, and their dependencies.

A Conceptual Data Model depicts the system’s content, organization, and essential business rules at a high level. Extending on our same example from before, a Conceptual Data Model for an eCommerce firm will include vendors, items, consumers, and sales.

Conceptual Data Model: Data Model Relationships | Hevo Data
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Logical Data Model

A Logical Data Model outlines the project’s data pieces and connections based on the Conceptual Data Model. For example, an analytical model in eCommerce demonstrates that goods are recognized by a “product ID,” which includes features such as a description, category, and unit pricing. You’ll see the names and details of specific entities in the database.

Data Architects and Business Analysts generally use the Logical Data Model to design a Database Management System, which is software that stores, retrieves, defines, and maintains data in a database.

Logical Data Model: Data Model Relationships | Hevo Data
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Data Model Relationships

Data Model Relationships describe business entities and their relationships. Below is a brief overview of some Data Model Relationships:

One-to-One Relationships 

When one item of data links to another in the database, it is called a One-to-One Data Model Relationship. For example, a person can only have one passport, and the passport can only belong to one person, as seen in the example below.

One-to-One Relationship Model: Data Model Relationships | Hevo Data
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One-to-Many Relationships

When a parent object has many offspring objects, it is said to be a One-to-Many Data Model Relationship. There is a Data Flow between the parent and the children. Parents, for example, may have multiple children, but the children belong to their single parent.

One-to-Many Relationship Model: Data Model Relationships | Hevo Data
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Many-to-Many Relationships

Many-to-Many Data Model Relationships happen when two one-to-many relationships happen via a join model. The image below shows that the Books have many Authors and the Authors have many Books. As a result, the join table exists and creates a Many-to-Many Data Model Relationship.

Many-to-Many Relationship Model: Data Model Relationships | Hevo Data
Image Source: Wikipedia

The Need for Data Integrity in Data Modeling

Data Integrity refers to data’s absolute correctness, completeness, and dependability. It indicates that your data is error-free: your measured values match the actual values and there are no mistakes, such as outdated information, redundancies, and typos.

Typically, businesses execute an array of error-checking and validation procedures, rules, and principles during the integration flow designing phase to preserve Data Integrity. Based on specified business rules, these procedures for inspections and corrections come into the picture. 

For example, there can exist a rule that states that the Data Model Relationship should filter out data with an invalid date or time value. When developing connections between various data items, keeping Data Integrity is critical. It ensures that data is accurate and moved from one phase to the next without errors.

Normalization in Data Modeling

A Data Modeling primer would be incomplete without discussing the concept of normalization. Normalization is the process of avoiding anomalies and eliminating redundancies

Normalization is a formal method of linking attributes with entities that use criteria. Normalizing in a Data Model Relationship organizes data so that each object has just one subject or topic. You can refer to it as deleting partial and transitive dependencies in more technical terms. 

There are various stages of normalization, beginning with the first normal form and progressing to the sixth normal form. The third normal form abbreviated “3NF“, is the most dominant. 3NF Data Model eliminates tables with unique records, including partial and transitive dependencies.

Normal Forms in RDBMS: Data Model Relationships | Hevo Data
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An excellent example to explain it is assuming you have the customer name, store, and purchase dollar value of a sale transaction. Suppose the customer gets married and needs to change the name, then it is a cumbersome activity to change it on all the transactions. All this data can get stored in a single table, and you could have hundreds or thousands of transactions done by a single customer leading to challenges in data modification. 

A normalized model will allow a single change to the customer’s name by storing customer data in a customer table, product data in a product table, store data in a store table, and linking tables together using primary keys and foreign keys.



Data Model Relationships are easy to construct once you understand their purpose and the process of following, collecting, organizing, and standardizing your data. They are essential in developing a database or information system and have a high impact on the quality and useful life of the system.

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Let us know your thoughts about understanding Data Model Relationships in the comment section below! We’d be happy to hear your opinions.

Sageena P Kunju
Freelance Technical Content Writer, Hevo Data

Sageena loves exploring data science and is passionate about making an impact in data teams' by unraveling the complexities of data integration and analysis through insightful content on intricate subjects.

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