Microsoft Power BI Cookbook

Error handling, comments, and variable names

In this example, the Product query is joined to the Product Subcategory query to add a column from Product Subcategory. The query includes error handling by wrapping both expressions with a try expression and an otherwise clause. If an error occurs, such as if the Product Subcategory query changes, the Product query is used for loading to the data model.

/* This query joins the Product query to the Product Subcategory query.    The product subcategory column 'EnglishProductSubcategoryName' is renamed 'Product Subcategory' */let ProductToProductSubCatJoin = try// Nested outer join based on Subcategory Surrogate KeyTable.NestedJoin(Product,{"ProductSubcategoryKey"},#"Product Subcategory",{"ProductSubcategoryKey"},"ProductSubCatColumns",JoinKind.LeftOuter) ...