Excel Power Query Data Cleaning and Refresh Notes
A practical Markdown note set for Excel and Power BI Power Query, covering connections, type conversion, merge and append, query steps and refresh troubleshooting for repeatable ETL workflows.
What this note set covers
These notes organize a repeatable Power Query workflow: confirm the input structure, import and clean data, apply typed transformations, merge or append queries, load a stable result and test refresh behavior.
The archive is a 9.24 KB Markdown note set, not a finished workbook, dataset or complete Power BI report. It is most useful when paired with a small, non-sensitive practice dataset.
Workflow boundaries
Query steps should be named and reviewed as a transformation record. Input paths, credentials, refresh permissions and downstream data models are separate operational concerns and must be tested in the current Excel or Power BI environment.
Maintenance note
This page was reviewed on 2026-08-23 against the catalog metadata. Preserve the input schema, query steps and refresh date with any adapted notes.
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Excel Power Query data cleaning and refresh workflow
Build the smallest repeatable query first, keep each transformation readable and test a replacement input before connecting the result to a report.
Before you start
- Use a Markdown reader and an Excel or Power BI version with Power Query support.
- Prepare a small, anonymized dataset with known row, column and key expectations.
- Record input paths, field types and refresh permissions separately.
Quick start
- 01
Confirm the input schema
List source files, sheets or tables and standardize column names, types, missing-value rules and the expected key.
- 02
Name the query steps
Add import, filter, type conversion, merge or append steps in a readable order and rename important steps by their purpose.
- 03
Check the result table
Compare row counts, keys, duplicate records and summary values to ensure a transformation did not silently drop or multiply data.
- 04
Test a refresh copy
Replace the input with another file of the same shape and record path, permission or field changes that affect refresh.
Usage tips
- Finish cleaning in the query layer before loading a stable result into a worksheet or data model.
- Apply type conversion early; mixed dates, numbers and text can change joins and aggregations.
- Keep a rollback copy and record the input range and refresh time after each change.
Troubleshooting and uninstall
Why can refresh not find the source file?
Check the path, file name, access permission and expected folder structure, then compare the replacement file's fields with the query schema.
Why did a merge suddenly increase the row count?
Inspect whether the join key is unique and whether a many-to-many match is duplicating rows; disable steps one at a time to locate the source.
Frequently asked questions
What problem does Power Query solve?
It turns import, cleaning, transformation and loading steps into a repeatable query that can be refreshed.
Are Excel and Power BI query steps identical?
The core transformations are similar, but loading location, data models and refresh permissions must be checked for each environment.
Does this download include a complete workbook or dataset?
No. It is a 9.24 KB Markdown note set; practice with a separate anonymized dataset.