Why this matters
Microsoft's Power BI Data Analyst certification lists preparing data as its first skill area, and in real jobs it takes much of the time. If the data comes in clean, with clear names and correct types, the model, measures and visuals that follow are simple. If it comes in messy, every later step fights you. The good news: you already know the tool, because Power BI uses the same Power Query you met in Excel.
Loading a file
On the Home tab choose Get data, then the source:
- Excel workbook: pick the file, and the Navigator window lists every sheet and table inside. Tick the ones you want. Excel tables (with names like
Sales) load more reliably than plain sheets. - Text/CSV: for exports from mobile money systems, survey tools such as KoboToolbox or ODK, and accounting software.
- Folder: combines many files with the same layout, such as one file per field officer.
At the bottom of the Navigator you have two buttons. Load brings the data in as it is. Transform Data opens Power Query first. Choose Transform Data almost every time; a minute of checking now saves an hour later.