Here is my code: SELECTAVG(ListPrice)ASavrg, ProductLine, SellStartDate FROMProduction.Product Msg 8120, Level 16, State 1, Line 13 Column 'Production.Product.ProductLine' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause. 1. What am I doing wrong? 2. Which SQL version is used on SQL Express? Is it standard SQL, T-SQL, something else?