How Do I Clean Up, Transform, and Load Data into Power BI?
“Learn how to load, clean, and transform data with Power BI in a matter of minutes. Quickly turn your raw data into meaningful insights that are meaningful for informed decision-making.”
It can be overwhelming at times to clean your data. This may also feel like digging through dirt for a hand full of treasure. The word "treasure" here translates into "valuable insights and trends."
For example, let's say you're a marketing analyst for a retail company. You have a massive dataset of customer transactions, and you need to analyze it to find answers for:
- Which products are selling the most?
- Which customers are the most loyal?
- Which marketing campaigns are the most effective?
- How can you positively impact your sales?
And so on . . .
You can use data analysis tools like Power BI to analyze how good you're with your personal finances. This amazing tool isn't limited to the world of businesses only.
Cleaning, transforming, and loading data in Power BI can feel challenging and like a nut job - like facing scrutiny for tasks you have to do repeatedly.
However, as you delve into the process of cleaning and transforming the data, you'll gradually uncover valuable insights akin to discovering shiny rocks amidst the dirt.
With continued analysis, those shiny rocks (metaphorically speaking) transform into golden nuggets. These nuggets provide significant insights that can empower you to make more informed decisions for your business.
The data cleaning, transforming, and loading in Power BI generally involves:
- Connecting to the data source in Power BI
- Using Power Query Editor, clean up and modify the data.
- Applying data cleaning operations like removing duplicates, filtering data, and handling missing values
- Performing data transformation tasks such as splitting columns, merging tables, and creating calculated columns
- Loading the cleaned and transformed data into Power BI
- Creating relationships between tables (if necessary)
- Building interactive visualizations and reports using the loaded data
- Publishing and sharing the Power BI reports with others
Let's see everything in detail.
Clean, Transform, and Load Data in Power BI: Detailed Explanation
Getting your data to a level where you can easily visualize it can be both challenging and rewarding. But with the right data analysis tool and data cleaning techniques, you can turn messy data into meaningful insights that can help you succeed.
So, to Clean, Transform, and Load data in Power BI, you can follow these simple steps:
Step-1: Connect to the Data Source
Start by connecting to the data source where your data is stored, such as a database or an Excel workbook.
Step-2: Clean the Data
Power BI offers a variety of tools to clean up messy data, such as removing duplicates, filtering out irrelevant rows, and sorting data by different criteria.
This is the longest step of all the steps. It can take some time. However, things get easier with time when you practice it a few times.
Cleaning the data is also referred to as “shaping the data.” Meaning, clean and shape (transform) the data before building reports.
Step-3: Transform the Data
When you’re done cleaning your data, use the Power Query Editor in Power BI to transform the data into the format you need for your analysis. To transform your data, select the Transform data button on the Home tab of Power BI Desktop. It will open Power Query Editor:
Note: It is recommended to record your data-shaping steps in Power Query Editor. Every time you connect to the data source, those steps are automatically applied. Your data will always be shaped as you intended. Power Query Editor operates on a specific view of the data, ensuring confidence in changes made to the source. You can view your steps and query properties in the Query Settings pane on the right side of the screen.
The data transformation step can include:
- Identifying Column Headers and Names
Identify column headers and names and evaluate their location for the correct position. See the screenshot below; the source data in the SalesTarget CSV file has product categories and monthly subcategories organized into columns.
- Promoting Headers
To handle the situation where a table in Power BI Desktop assumes that all data belongs in table rows, but there’s a first row containing column names like in the previous SalesTarget example, you can correct this by promoting the first table row into column headers.
There are two ways to promote headers:
1. On the Home tab, select the "Use First Row as Headers" option.
2. Alternatively, select the drop-down button next to Column1, and choose "Use First Row as Headers."
- Renaming Columns
To examine the column headers and address potential issues such as incorrect headers, spelling errors, or inconsistent naming conventions, follow these sub-steps:
1. Refer to the previous screenshot that shows the impact of the "Use First Row as Headers" feature. Notice that the column containing subcategory Name data now has an incorrect column header, labeled as "Month."
2. To rename column headers, you have two options:
- Right-click the header, select "Rename," change the name, and press Enter.
- Double-click the column header and overwrite the name with the correct value.
3. Renaming the columns to their proper names after eliminating (skipping) the first two rows is another option.
- Removing Top Rows
To remove rows from your data during the shaping process, follow these steps:
1. If you encounter top rows that are blank or contain irrelevant data for your reports, you need to remove them.
2. In the SalesTarget example, see that the first row is blank, and the second row contains data that is no longer needed.
3. To remove these excess rows, go to the Home tab and select "Remove Rows" followed by "Remove Top Rows."
- Eliminating Columns
To remove unnecessary columns during the data shaping process, follow these steps:
1. It is ideal to remove columns as early as possible in the process, even at the data extraction stage. For example, in SQL, you can use a column list in the SELECT statement to limit the extracted data to only needed columns when working with relational databases.
2. Removing columns early is especially important when you have proven relationships between tables. Removing unnecessary columns allows you to focus on the essential data and improves the overall performance of your Power BI Desktop datasets and reports.
3. Examine each column and determine if the data it contains is truly needed. If a column doesn't contribute to your reports, it adds no value to your data model and should be removed. You can always add the column back later if requirements change.
4. To remove columns, you can use either of the following methods:
- Select the columns you want to remove, then go to the Home tab and choose "Remove Columns."
- Unpivoting and Pivoting Columns
Unpivoting is a valuable feature in Power BI, often utilized when importing data from Excel. Initially, the data appears understandable, but making calculations across rows becomes challenging. Your objective is to present the data in Power BI with different columns.
Unpivoting simplifies the process of creating DAX measures for the data in the future. By completing this step, you establish a more straightforward approach to slicing the data using the defined columns.
When dealing with flat data that lacks structure or grouping, it can be challenging to identify patterns. To address this, you can use the Pivot Column feature in Power BI to convert the flat data into a table with gathered values for each unique entry in a column.
In the SalesTarget example, you can pivot the columns to determine the number of product subcategories within each product category. Here's how to do it:
1. Go to the Transform tab in Power Query Editor.
2. Select Transform > Pivot Columns.
3. In the Pivot Column window, choose a column from the Values Column list (e.g., Subcategory name).
4. Expand the advanced options and select an option from the Aggregate Value Function list (e.g., Count (All)).
5. Click OK to proceed.
Remember: Power Query Editor logs all data-cleaning steps in the Query Settings pane. Once you've made all required changes, select Close & Apply to close the editor and apply the modifications to your data model. However, before closing, you can execute additional data cleanup and transformation tasks within Power Query Editor, which will be discussed later in the module.
Step-4: Apply Data Modeling
In Power BI, you can create data relationships between different tables, create hierarchies, and define measures, which are calculated values used in charts and tables.
Step-5: Load data into Power BI
Once you have cleaned, transformed, and modeled your data, you can load it into Power BI.
From there, you can create visualizations:
Power BI Data Cleaning FAQs (Frequently Asked Questions)
Why is it necessary to perform Data Cleaning in Power BI?
Data cleaning in Power BI is essential to ensure accurate and reliable analysis by addressing issues such as missing values, duplicates, inconsistencies, and formatting errors that can hurt data quality and analytical results.
What is used to clean and transform data in Power BI?
Power Query Editor is used in Power BI to clean and transform data, providing functionalities to shape, filter, merge, and manipulate data from various sources before loading it into the data model for analysis.
How do you load data in Power BI after transformation?
After transforming the data in Power Query Editor, you can load it into Power BI by selecting "Close & Apply." This action applies the changes made in Power Query Editor and loads the data into the data model for further analysis and visualization in Power BI.
How do I cleanse data in Power BI?
In Power BI, you can cleanse data using various data cleaning techniques such as handling missing values, removing duplicates, correcting inconsistencies, standardizing formats, and applying data validation rules.
These cleansing tasks can be performed in the Power Query Editor by utilizing its robust set of data transformation and cleaning capabilities
Do you load or transform data in Power BI? What's the difference?
In Power BI, you both load and transform data. Loading data refers to bringing the data from a source (such as a database or file) into Power BI for analysis.
Transforming data involves manipulating and shaping the loaded data using Power Query Editor to clean, filter, merge, aggregate, and derive new insights before visualizing and analyzing it in Power BI.
The difference is that loading brings data into Power BI, while transforming involves changing and preparing the data for analysis.
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