Clean Super Messy Tables Using List.Transform & List.Skip (Advanced M Code Tutorial)

#PowerQuery #PowerBI #ExcelTips #DataCleaning #MCode #PowerQueryChallenge #DataTransformation #ExcelPowerQuery #BusinessIntelligence #DataAnalytics #OmidMotamedi #PowerQueryTutorial #AdvancedMCodeIn In this Power Query challenge 313, we clean a messy hierarchical table where values shift across multiple columns. Using advanced M techniques — including List.Transform, List.Skip, List.FirstN, and custom list operations — we reconstruct clean rows and extract meaningful data such as Date, Product, Customer, and Quantity. In this step-by-step tutorial, you’ll learn: ✅ How to detect non-null values across multiple columns ✅ How to rebuild structured rows using list functions ✅ How to apply: Table.FromRows(List.Transform(Source, each List.FirstN(List.Skip(_, each _ = null), 4))) ✅ How to handle misaligned data common in real-world Excel files ✅ How to convert the output into a reusable Power Query function This video is perfect for analysts working with messy Excel data, Power BI, or Power Query transformations. If you enjoyed the video, don’t forget to Like, Subscribe, and leave your questions in the comments! 00:00 Introduction 00:45 List.Skip in example 02:45 Convert Table to List 03:20 List.Transfrorm 05:40 List.FirstN