Creating a logical data model (LDM) is the second step in database development after the conceptual data model (CDM), showing important data and relationships between tables. The LDM is detailed with titles and relationships but no actual data, making it easier for engineers to build the physical data model (PDM).
In systems engineering and database development, creating a logical data model (LDM) is the second step in creating the entire data model, after the conceptual data model (CDM) and continued by the physical data model (PDM) . In the logical data model, engineers target the data that is important to the business and show the relationship of the entire database from one section to another. The LDM diagram will show several tables with data titles, but the actual data will not be present. For example, if a table of dates is created, the LDM diagram will show titles such as “Month” and “Year”, but the actual month and year values will not be present.
When it comes to data mapping, the first model is the CDM. This diagram is a simple concept that starts with data modeling. There will be several tables, without any titles, and there may be a few rows to show relationships.
After the conceptual model, the logical data model is built. This template is much more detailed in terms of titles and relationships. Empty tables are filled with arbitrary values so engineers know which data is important. For example, the conceptual model will have a table named ‘Store’, while the LDM will populate the table with titles such as ‘Store Description’ and ‘Store Name’. The data is not implemented at this stage, which is just intended to let engineers know what information is needed for a functioning database.
The relationships between the different tables are also detailed, so engineers will know how to make them interact. There is usually one central table, to which all other tables connect. Between auxiliary tables, there are sometimes interconnections, which shows that these tables cannot work independently of each other. Lines connecting one table to another show these relationships.
A logical data model is needed for many reasons. Clarifies what information the company is collecting and how all the data is related. This also makes it easier for management to review the draft and see if more information is needed. The information is represented in diagrams, so engineers need less time to build the data model because the plan is detailed and there is no guesswork.
After the logical data model, the PDM is created. This is the real, physical implementation of the database. In this model, all arbitrary values are filled with real values, for example “Year” is filled with “2011” and the data is actually used and collected.
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