What is transformation using SQL SELECT expressions?

< 1 min read

Transformation using SQL SELECT expressions means modifying data while extracting it from the source.
We apply calculations, filters, and joins directly in the SQL query.
In my project, we calculated Profit = Revenue – Cost in the SELECT statement itself.
We also filtered only last 12 months of orders using WHERE clause.
Columns were renamed using AS for business-friendly names.
Joins combined Customer and Order tables before loading into Power BI.
Aggregations like SUM, AVG, or COUNT were performed in SQL to reduce data volume.
This reduced processing needed in Power Query or Power BI model.
Helps improve refresh performance and minimizes network load.
So SQL transformations prepare clean and analysis-ready data at source.

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