DEV Community: MG-Stella

HOW TO ALTER CHAOTIC DATA IN POWER BI

MG-Stella — Mon, 09 Feb 2026 16:58:43 +0000

POWER QUERY
Power Query is a tool in power Bi that is used to clean, transform and prepare data.
By using power query you could perform the following:
filter and sort data
manipulate column to your preference
Clean data
merge and append queries

FILTERING AND SORTING
Filtering and sorting data helps one focus on the most necessary information in ones dataset

DATA CLEANING

Data cleaning is all about clearing "noisy" unrelatable data from your dataset leaving you with important data that will give correct valuable insights.

_Removing duplicates_

To remove duplicates in a datasets is essentials for it may alter the results.

To remove null values or blanks_

For null values one should replaces them with NOT PROVIDED for text or 0 in number formats

MERGING AND APPENDING QUERIES

Merging queries is combining two or more existing tables to one for easier access.
Appending Queries- is when you want to modify or extend the contents of a query, especially when the data is from separate reports or files.

COLUMN MANIPULATION
Column manipulation allows you to add or remove a column in your data.

DATA SHAPING
Data shaping in power query helps the user transform data into your preferred need.
-_Pivoting and unpivoting table - Pivoting tables restructures table, by converting rows into columns and Unpivoting tables converts wide tables to long formats. They both help in better analysis of datasets.

DAX

Data Analysis Expression (DAX)
DAX is used to perform advanced calculation and queries o data

DAX FUNCTIONS
Here are some of the basic DAX functions that are used in power bi :
AGGREGATE FUNCTIONS

1- AVERAGE -

SUM - it add ups the values of the selected column
MIN -it finds the minimum value in a given column
MAX - it identifies the highest value in a column

LOGICAL FUNCTIONS
AND - Combines two logical expression to give a result
OR - It gives a result if at least one or multiple conditions are true, false
NOT - it checks if one value is not equal to the other
IF - it makes a logical comparison between a value and the condition set.
ITERETATIVE X FUNCTIONS
X- FUNCTIONS are used when there is need to perform a preliminary action before a simple aggregation of a column.
The X functions perform row by row calculations taking each row to account and allowing complex calculation that aggregate functions cannot handle.
Examples:
SUM (X) - Sum
AVERAGE (X) -Average
MIN (X)- Min
MAX (X) - Max
COUNT (X) -Quantity

TIME INTELLIGENCE
Time intelligence functions in DAX are used for analyzing trends based on time.

POWER BI : MODELLING AND SCHEMAS.

MG-Stella — Mon, 02 Feb 2026 17:30:08 +0000

HEY THERE.

TERMS
DATA MODELLING - Data Modelling is the process of analyzing, organizing and defining data using visual representation, to highlight trends , reveal patterns amd relationships between the data.
A schema - A schema is a formal description structure of a database.

A fact table - A fact table is the main table that is used to describe events that have taken place.
*A dimension table *-A dimension table also called lookup is a table that holds information about categorical fields in the fact table. It describes the features of a dataset.

DATA MODELLING
Types of data model

Conceptual Data Modelling A conceptual data model is mainly used for business concepts. It mainly focuses on understanding and identifying the business terminology and concepts and how they relate.

The conceptual data model helps one get a better understanding of what to take into consideration by looking at the the "bigger picture" based on the solution of your data.

Logic Data Model

Unlike the conceptual data model, the logic model is more detail and precise .
A logic data model provides a more detailed view of how entities relate to each other and the attributes associated with each entity guiding the implementation phase .
This model acts as a practical step towards the implementation of data.

Physical Data Model

A physical data model specifies how data is stored and accessed in a specific database system. It requires the knowledge of the database management system (DBMS) indexing, compression and distributing options.

Its purpose is to store data in a robust manner that enables high performance and takes into accounts the technical detail of the
chosen technology.

Physical models deals with downstream data that already exist with predefined schemas, which should not be lost in the process of integration in order to get correct data types and metadata.

For a good data model practices the following should be done:

One should limit data imports to enhance great performance
Turning off time intelligence- When on it automatically creates a date/Time Hierarchy, and when a hierarchy is created an additional table is added which can bloat the power bi causing a slow down in rendering the visuals.

**
SCHEMAS
**
I) STAR SCHEMA

In a star schema a fact table is at the center while dimension table are positioned at each point of the star.

A fact table is made up of values that can be summarized and aggregated as well as one or many keys that link dimension tables.

The key is used to create a link or connection between tables.

The star arrangement allows easy navigation and analysis of data.

A star schema can be used when you need simple ,fast queries and straightforward model.
It can also be used for quick insights by business users.

II) SNOWFLAKE SCHEMA

A snowflake schema is a variation or extension of a star schema where dimension tables are normalized, meaning they are broken down into additional related tables.

A snowflake can be used when:

-Your data has high level of complexity or maintaining data integrity and reducing redundancy.

-Can be used in data warehouse where detailed analysis and reporting are required.

RELATIONSHIP IN POWER BI

Types of Relationships in POWER BI

I) Direct Relationship - This is a connection between two tables.
The tables are linked based on one or more common fields.

II) Multiple Relationships -This a connection or link between two or more tables in power bi.

III) Cross -Filter Direction- Cross -Filtering determines how filters applied in one affect related tables in the relationship.

A LIGHT GUIDE THROUGH EXCEL FOR A DATA ANALYST

MG-Stella — Mon, 26 Jan 2026 09:42:08 +0000

HEY.
They say as an data analyst starting with excel is the easiest and first way to begin your journey in your aspiring field. With this guide it will help you ease your learning in excel.
Feeling overwhelmed , confused and don't know where to start learning ?.Keep calm
On this article will focus mostly on simple areas that are quick to learn as you progress and are mostly inquired when working with data in excel as a data analyst.

starting off this are shortcuts you can use to help you maneuver through and help you to be more efficient while learning your way through MICROSOFT Excel.

__FILE SHORTCUT

New ctrl + N
Open ctrl + O
Save workbook ctrl + S
Save as F12
Go to next workbook ctrl + Tab ten
Close file ctrl+ F4
Close all open excel files Alt + F4

_DATA EDITING SHORTCUTS _

Fill down from cell above Ctrl + D
Fill right from cell left Ctrl + R
Find and replace Ctrl + F
Filter data Ctrl + Alt + L

**Functions in excel
_Aggregate functions
Sum - Sum is used to calculate the total number of data in given set.

Average - Average is used to calculate the arithmetic mean of a given set in excel.

Max - Max is used to show the highest value in a given data set.

Min - AS opposed to to max this is used to show or highlight the lowest number.

Count - For count it is used to show the the total numeric values in a cell.

Count A -This is used to show the total number of cells that are not blank. They can either be numeric values or texts.

_logical function_
logical Functions are used to automate decision making

_*if* function_
The if function is made of 3 parts
I).A condition.
II). What to do if the condition is met.
III). What to do if the condition is not met.

_look up functions_
I). V-Lookup function -is used to search for values in a vertical order.
The v-lookup function may be slow when used in large data sets.
II).horizontal Lookup -H-lookup is used to retrieve information from a table by searching for values in a row.

Conditional Formatting
Conditional Formatting is used to highlight cells with important values or to be able to see trends in a given data by using bars, icon or different colors to easily visualize it.

NOTE: The condition for the cell was to highlight the performance score that is greater than 4.

**
PIVOT TABLES

A pivot table is used for organizing, summarizing and for analysis of complex data sets.
It can also be used to create reports or help give insights .
Slicers in pivot tables are used to filter data and actively interact with the data.
How to create a pivot table and slicer

In your dataset you go to to insert pivot table. A new sheet will be created like shown above. On your right you can use the pivot table fields to insert your data of choice into rows, filters, values and column to summarize it.

To insert a slicer .

click in the pivot table created.
Then go to insert tab and and toward the far right you will see slicer click on it.
The slicer will give you options depending on your dataset. choose the slicers you prefer and insert
to refresh the slicer or delete it.You can double click on the slicer created and opt for the remove or delete menu given.

Happy learning.