Power Query Merging

Hi Alka,

This typically means the merge operation was initiated, but the expected data from the second table isn’t visible in the result. This is often due to one of the following:

Mismatched join keys
Incorrect join type
Failure to expand the merged column
Data type mismatches
Hidden nulls or blanks in key columns

Steps for you to check
1. Check the Join Columns
Ensure both tables have a common column selected for the merge.
The data types of the join columns must match exactly (e.g. both should be text or both should be numbers).
In Power Query, select the column → right-click → Change Type → choose the correct type.

2. Verify the Join Type
Go to Home > Merge Queries.
In the merge dialog, check the Join Kind:
Inner Join: Only matching rows from both tables.
Left Outer Join: All rows from the first table, and matching rows from the second.
If you expect all rows from the first table regardless of matches, you should use Left Outer Join

3. Expand the Merged Column
After merging, Power Query adds a new column with a small table icon.
Click the expand icon (⤢) in the column header.
Select the fields from the second table that should be included in the final result.
If this step is skipped, the merge appears to have happened but no data is visible.

4. Check for Nulls or Blanks
If the join column contains blanks or nulls in either table, those rows won’t match.
Use the Filter or Remove Empty options to clean the data before merging.

5. Preview the Merge Output
After expanding the merged column, scroll through the preview to ensure data has pulled through.
If the column shows “null” for all rows, it means no matches were found—likely due to mismatched keys or data types.
6. Use Diagnostics (Optional)
Enable Query Diagnostics from the Tools tab to trace where the merge might be failing.

Additional things to consider
Sort and Compare: Before merging, sort both tables by the join column to visually inspect for mismatches.
Trim and Clean: Use Text.Trim() or Text.Clean() in a custom column to remove hidden characters that might prevent matches.
Preview Join Results: Create a temporary table with just the join columns to test the merge logic.

Please run through those steps and then let us know if you are still having the same issue when trying to implement what you learnt on the course.

To manage the expectation, this support forum will help you embed the learning as you work on your own files, it isn't a consultancy service to solve the problem for you

Kind regards

Richard

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