I am using the unpivot transformation, but I can not figure out how to use an expression in the Pivot Key Value.
The denormalized table I want to unpivot has columns like Sunday_Qty, Monday_Qty, Tuesday_Qty, etc. Just before the unpivot component, I inserted a derived column component that adds fields like DateSun, DateMon, DateTue, etc. that resolves to values like 01/07/2007, 01/08/2007, etc.
So for the various rows in the Unpivot Transformation Editor, I entered DateSun, DateMon, DateTue, etc. for the Pivot Key Value, and "EntryDate" for the pivot key value column name.
The data pipeline gets unpivoted correctly, but the rows have the literal values "DateSun", "DateMon", etc. in the EntryDate column.
How do I tell SSIS to use the DateSun column instead of the string "DateSun"