Using a Reference Table as the Primary Table in Power BI

Problem Analysis

In Power BI, users often create multiple queries and apply various transformations through the Power Query Editor. When utilizing a reference table—created from an existing query—to retain certain steps, there may be confusion about whether it can serve as the primary table to remove previously applied steps from the original query.

Understanding Reference Tables

A reference table in Power BI is essentially a copy of another query that maintains a connection to the original data source. This means any changes made to the original query can be seen in the reference table unless additional transformations are applied to modify them.

Key Points:

• Reference Table: A duplication of an original query that can be transformed independently.
• Applied Steps: Transformations that modify data within the Power Query Editor.

Strategy to Remove Steps

1. Create the Reference Table

To use a reference table effectively, first ensure that you have a reference table created from your primary table.

• Select your primary query in Power Query.
• Right-click on the query and select Reference. This creates a new query that references the original.

2. Remove Applied Steps

If your goal is to remove all transformation steps applied to the original query, you can do so in the reference table. Here’s how:

• In the Power Query Editor, select the reference table.
• In the Applied Steps pane, you can either remove individual transformation steps by clicking the "X" next to each step, or you can reset the reference table completely.

3. Reset the Reference Table

To entirely reset the reference table and remove all transformations:

• Right-click the reference table in the Queries pane.
• Select Advanced Editor.
• Edit the code to directly reference the original table without any additional transformations.

Here's an example of code adjustment to reset it to the base state:

let
    Source = YourPrimaryTableName
in
    Source

4. Validate Changes

After making any changes:

• Click Close & Apply to save modifications and ensure they reflect in your Power BI report.

Comprehensive Advice

1. Start Fresh: If you are aiming to keep the reference table clean without prior transformation steps, use the Advanced Editor to directly pull in data from the primary table.

2. Monitor Source Changes: Be mindful that any adjustments in the original table's structure (like removing columns or changing data types) may impact the reference tables.

3. Utilize Multiple Queries: If you intend to keep different versions or transformations, consider utilizing multiple reference tables instead of over-complicating a single query.

4. Performance Considerations: Excessive transformations and multiple layers of queries can affect performance. Optimize queries by removing unnecessary steps.

Conclusion

Using a reference table as the primary table to clean up transformations is not only possible in Power BI but can also enhance the clarity and performance of your data models. By understanding the relationships between your primary and reference tables, you can effectively manage and streamline your data analysis process. For advanced techniques, consider exploring training and resources available on the Enterprise DNA Platform.