Data Science Tales

In the previous blog post, we covered Data Modeling. We have seen that data modeling is really important before jumping into predictive modeling.  In this article, we will cover the Relational Data Model (RDM). Let's start from the very basics, relational means anything which is linked with some other thing. This link is called "Relationship". In RDM or RM there are major three types of relationship cardinalities (also called Multiplicities or Cardianalities): 1. One to one 2. One to many 3. Many to many We can understand these with the help of a few simple examples;  One to one: One department has one manager. One to many: One class has many students. Many to many: Many teachers can teach many students. Okay, so we have got an abstract overview of the term " Relational ", now the next thing is " Data ", data covers everything, anything... And finally, " Model " means something in the form of a template, design, a kind of blueprint.  To store

source: https://searchdatamanagement.techtarget.com/definition/data-modeling A wise person once said a picture is worth a thousand words . In real-world data is not just a few rows of excel sheet, yet it comprises several billion rows expanded through hundreds  of tables. A table is usually made up of rows and columns. Each table represents an Entity . Entity means an Object or thing. That Entity has several properties called Attributes . Those attributes represent the qualities or characteristics of the entity. Since there is more than one entity, so there should be a Relationship between those entities. If we look at the tables we cannot get a clear idea of the relationship between several tables/Entities. Hence, we need to represent the tables/data in the form of a picture or a flow graph. That flow graph or Entity-Relationship diagram is called a Data Model .  Data Modeling is a technique to represent how the tables are related to each other and to represent the structure of da