Chapter 1

  

Principles of Database Normalization:

Whenever we load any data into Query editor then I performed two steps

a.Rename Table name under Properties section

b.Go through Column header and make sure header data type are correct

Normalization is process of organizing the tables and columns in a relational database 

to reduce redundancy and preserve data integrity . 

It's commonly used to :

1)Eliminate redundant data to decrease table sizes and improve processing speed & efficiency 

2)Minimize errors and anomalies from data modifications(inserting ,updating and deleting records)

3)Simplify queries and structure the database for meaningful analysis

TIP : In an normalized database ,each table should serve a distinct and specific purpose ( i.e  product information ,dates , transaction ,records ,customer attributes ,etc  .)

DATA TABLES VS. LOOKUP TABLES :

Models generally contain two types of tables : data (or fact) tables and lookup(or "dimension") tables

-Data tables contain numbers or values , typically at granular level ,with ID or "key" columns that can be used to create table relationships.

-Lookup tables provide descriptive, often text based attributes about each dimension in a table

--Primary key are unique and Foreign key can be multiple 

Merging Data from different tables into one tables creates redundant data and utilize significantly more memory and 

processing power than creating relationships between multiple small tables 

Creating "SNOWFLAKE" SCHEMAS:

There are two type of Relationship in PowerBI :

1)Active Relationships

2)InActive Relationships 

Relationship cardinality :

Connecting Multiple Tables :

Understanding Filter Flow :

Filer flow Downstream from Lookup Table to Data table .

Two Way Filters :

In this case we have enabled two way cross filtering between the Sales  table and Territory lookup  

It is very important to have good fundamental understanding of Data Model and Filter in PowerBI:

Data Tables generally has Foreign keys and Look up tables has Primary keys