Power Query Overview Lecture Notes

Introduction to Power Query

• Power Query is a tool in Excel and Power BI for data transformation and automation.
• Reduces task time from hours to minutes.
• Available in Excel versions 2010 onwards and Power BI Desktop.
• Requires no programming knowledge; uses GUI for transformations.

Availability

• Excel 2016 or later: Power Query is found on the Data tab in the Get and Transform group.
• Excel 2010 or 2013: Downloadable free add-in, appears as its own tab.
• Not available in Excel 2007 or earlier.
• Same tool in Excel and Power BI; learn once, use in both.

Benefits of Using Power Query

• Automates data gathering and cleaning.
• Saves time spent on laborious data handling tasks.
• Survey: 40% of data specialists and 80% of analysts' time spent on data prep.

Capabilities

• Processes data from various sources:
  • Excel worksheets, other Excel files, text/CSV files, PDFs, JSON, XML, databases (SQL, Access), cloud-based systems (Azure, SharePoint), etc.
• Transforms messy data into a tabular format easily.
• Utilizes a GUI for common data cleaning tasks.

Practical Example

• Scenario: Cleaning and combining sales data from multiple Excel files.
• Steps:
  • Correct headers, split columns, calculate sale amounts, extract text, calculate days between dates.
  • Automate these steps for future files in the folder.

Transformation Process with Power Query

1. Fix Headers:
   • Remove auto-promoted headers, merge split headers.
2. Transform Data:
   • Transpose to re-organize headers, merge columns, split data using delimiters.
3. Add Calculations:
   • Calculate new columns (e.g., Sale Amount, Days to Ship).
   • Use formulas similar to Excel.
4. Data Cleaning:
   • Handle text split for first name, remove unnecessary data.

Loading and Updating Data

• Combine data from all files into a single table.
• Use all previous transformations on new files automatically once added to a folder.
• Data Type Detection:
  • Set proper data types to ensure Excel handles data correctly.

Utilizing Transformed Data

• Load data into PivotTables or PivotCharts for analysis.
• Easily update with new data by adding files and refreshing data.

Conclusion

• Power Query significantly enhances efficiency in data handling tasks.
• Point-and-click interface eliminates need for programming.
• Encourages experimentation and learning for improved productivity.

Additional Resources

• Course links and tutorial files available for deeper understanding.
• Encourage sharing with colleagues who might benefit from Power Query.