What is a logical data model?

In system engineering and database development, the creation of a logical data model (LDM) is the second step in creating the entire data model that comes after the conceptual data model (CDM) and proceeds with the model of the physical data (PDM). In the logical data model, engineers focus on important business data and show the relationship of the entire database from one section to another. The LDM diagram displays different tables with data names, but the actual data will not be present. For example, if the data table is made, the LDM diagram displays names such as "Moon" and "Year", but the actual values ​​of the moon and year will not be present.

When it comes to data mapping, the first model is CDM. This diagram is a simple concept that begins with data modeling. There will be several tables, without any titles in them, and there may be some lines that would show relationships.

After the concept model, a logical data model is created. This model is much more detailed in terms of titles and relationships. The empty tables are full ofThe values, so engineers know what data is important. For example, the conceptual model will have a table called "Store", while LDM will fill the table titles such as "Trade Description" and "Trade name". The data is not implemented at this stage, which intends to let engineers know what information is required for a functional database.

Relationships between different tables are also detailed, so engineers will know how to get them to interact. Usually there is one central table to which all other tables are joined. There are sometimes interconnections among the complementary tables that show that these tables cannot function independently of each other. The lines connecting one table with another show these relationships.

The logical data model is needed for many reasons. It explains what information is collecting and how all the data is connected. It also makes management easier to see the proposal and see if it isMore information is needed. The information is diagramped, so engineers will need less time to create a data model because the plan is described in detail and there is no guessing.

After a logical data model, PDM is created. This is the real and physical implementation of the database. In this model, all any values ​​are full of actual values, such as the "year" filled with "2011" and data are actually used and collected.