When working with Power Query, you’ll often need to combine data from multiple tables. Two powerful methods to achieve this are Merging Queries and Appending Queries. But how do these methods differ, and when should you use each one?
In this guide, we’ll explore the key differences between merging and appending queries and provide practical examples to help you optimize your data transformation process.
1. What is Merging Queries in Power Query?
Merging Queries allows you to combine columns from two or more tables based on a matching key or shared column.
Use Case for Merging:
- When you need to bring in additional columns (like combining product data with sales data).
- When you have relational data with common fields (e.g., customer ID).
How to Merge Queries:
- Go to Power Query Editor and select Merge Queries.
- Choose the main table and the related table to merge.
- Select the key column(s) that link the two tables.
- Define the join type (e.g., Left Join, Inner Join).
- Click OK and expand the merged table to add the desired columns.
Types of Joins in Power Query:
- Left Join: Keeps all rows from the first table and matching rows from the second.
- Right Join: Keeps all rows from the second table and matching rows from the first.
- Inner Join: Keeps only matching rows from both tables.
- Full Outer Join: Keeps all rows from both tables.
2. What is Appending Queries in Power Query?
Appending Queries stacks data from two or more tables on top of each other, essentially combining rows rather than columns.
Use Case for Appending:
- When you have multiple tables with the same structure (e.g., monthly sales data).
- When you want to create a unified dataset from different time periods or regions.
How to Append Queries:
- Go to Power Query Editor and select Append Queries.
- Choose the tables you want to append.
- Click OK, and Power Query will stack the rows together into one combined table.
3. Key Differences Between Merging and Appending Queries
| Feature | Merging Queries | Appending Queries |
|---|---|---|
| Purpose | Combine columns based on matching keys | Stack rows from tables with the same structure |
| Result | One table with expanded columns | One table with combined rows |
| Best Use Case | When working with relational data | When consolidating datasets |
| Complexity | Requires defining key columns and join types | Simple stacking operation |
4. When to Use Merging vs. Appending
Use Merging Queries When:
✅ You’re working with relational tables (e.g., Customers and Orders).
✅ You need to enrich your main dataset by adding additional columns.
✅ You want to combine data based on specific matching keys.
Use Appending Queries When:
✅ You’re consolidating data from multiple files or sources with identical structures (e.g., sales reports from different months).
✅ You need to stack rows to create a unified dataset.
✅ You’re handling periodic data and want to combine it into a master table.
5. Can You Use Merging and Appending Together?
Yes! In many real-world scenarios, you might need to use both merging and appending.
Example Workflow:
- Append Queries to consolidate sales data from January, February, and March.
- Merge Queries to combine the consolidated sales data with product details based on Product ID.
- Load the final combined dataset into Power BI for further analysis.
Conclusion
Both merging and appending queries are essential tools in Power Query that help you combine data efficiently. By understanding their differences and use cases, you can optimize your data transformation process and create cleaner, more unified datasets,
Mastering these techniques will improve your Power BI reports and streamline your data preparation tasks!