Project Management and Information Management professional, Liselle Ramcharan-Briscoe, continues the data adventure by sharing with us how by understanding a company’s business rules, and by using Logical Data Models, a company can achieve even greater success!


I love Logical Data Models. I strongly believe that if you want to understand how to maximise the use of the data available in your company, that you need to outline your business rules. In my mind, the best way to do so is to develop your Logical Data Model (LDM).

What is an LDM anyway?

Techopedia defines a logical data model as follows:

A logical data model (LDM) provides a detailed overview of the entire set of data created and maintained by an organization. It is a diagrammatic presentation of the organization’s data and its representation is independent from the underlying database technology.

The key points to absorb from this definition are that an LDM:

  1. Represents your company’s data
  2. Shows data that is generated as part of your company’s business processes
  3. Is a visual representation of your company’s data
  4. Is independent of the database that the data is captured.

The realities of the LDM

Often, the reality that you may face is that your company does not have an LDM. There may be a general understanding of the data generated and the relationships, but time has never been taken to understand the “big picture”.

An important reality of the LDM is that it does not always represent the final way in which the data is actually stored in the company. Data may actually be stored across multiple systems, or when you review the data stored in the database, it does not look like the beautiful illustration that was shown to describe what happens in the business. That’s okay – it does not have to. Often the final database is designed for optimal performance. Entities used to explain concepts may physically reside in the same table.

Consider your company – data is generated via various processes and systems that support the business. Data may not neatly reside in one database. For this reason, I believe LDMs become even more important to your company. Why? Because beyond illustrating the data that resides in your company, it shows your company’s business rules.

Business Rules? What Business Rules?

A business rule is a basic definition or constraint about how a business operates. As such, the answer to the rule is either ‘True’ or ‘False’. An example of a constraint is, ”My company can only sell to persons over the age of 18”. An example of an operation is, “I can have one valid contact at a time with a company”.

Business rules allow you to state what your business does in simple statements. The focus is on the major entities that are key to your business, and the relationships that exist amongst these entities. The entities are key business concepts that are fundamental to your company, a common example is your CUSTOMER.

LDM example

To illustrate how your business can be represented by an LDM, here is a description of a business and how it can be represented.

My company has two areas of focus, carpentry and plumbing. I only provide my services to individuals (versus companies), and I only hire persons who are specialists in one service or the other.

Based on this statement, what are my business rules?

  1. There are two services offered, carpentry and plumbing
  2. Services are only provided to individuals
  3. An employee is a specialist in one service
  4. An employee can only serve individuals who require the service for which they are a specialist.

Figure 1 is a simple illustration of these rules. Not all the data elements that would be used by a company to define that business concept (entity) but sufficient to confirm the relationships.

Figure 1: Simple LDM to illustrate business rules (Source: L Ramcharan-Briscoe)


How can my business rules change?

  1. I can offer an additional service, Electrical Work
  2. I can offer services to companies
  3. I can hire employees are specialists in at least one service

Figure 2 illustrates the updated data model would look like.

Figure 2: Updated LDM to illustrate the updated business rules (Source: L Ramcharan-Briscoe)

(Please note: The importance of the illustration is not to give a crash course in data modelling but to provide a visual on how changes to your business rules impact the additional data that becomes important to your business.)

 Reverse Engineering

Often, where a company finds itself having to reverse engineer its LDM. This happens because the business rules are a part of the organic knowledge, and no formal documentation has been put in place to collect that knowledge. If there happened to be documentation, as a result of a project, often no process has been put in place to keep the documentation current.

This may seem a little abstract, but let’s consider reporting. When data needs to be gathered for reporting purposes, typically there is a huge effort to collate that data into one place. Ideally, a central database is the starting point. When an LDM does not exist, a person or team is tasked with the job of “putting the pieces of the puzzle together” to ensure that what is stored actually reflects the business.

Parting thoughts

Creating an LDM can be time consuming. The more processes your company has in place, the higher the probability that you have many relationships and entities to consider. Take the time to create your logical data model. Validate it with both business and technology. If used correctly, it allows changes to how your gather your data to become significantly easier, and any change in business process that affects your business rules can then be more easily translated into how you collect your data. Data is Queen! And gathering it effectively keeps you in charge of your queendom!



Image credit:  geralt (Pixabay)