Hello there. I've a question about a query I want to create in MsAccess. (I understand the basics of SQL.)I am running a webshop and I want to be able to analyse the orders. Therefore I want to create a list with all categories and the sales/turnover within that category within in month. So, for example: Date | Category | Turnover(amount)2009-01 | Softdrinks | 40002009-01 | Coffee | 20442009-01 | Tea | 52952009-02 | Softdrinks | 60002009-02 | Coffee | 11562009-02 | Tea | 7234etc.etc.My database looks like this:NavigationGroupNavigationGroupID | DescriptionProductGroupProductID | NavigationGroupID.OrderHeaderOrderID | CreationDateOrderProductProductID | OrderID | Amount | PriceI created this SQL Query, but Access is running out of memory when I want to run it. What am I doing wrong?SELECT YEAR(oh.CreationDate) AS year, MONTH(oh.CreationDate) AS month, ng.Description, SUM(op.Amount) AS totalFROM NavigationGroup ng, OrderHeader oh, OrderProduct op, ProductGroup pgWHERE YEAR(oh.CreationDate)=2009 AND op.OrderID=oh.OrderID AND op.ProductID=pg.ProductID AND pg.NavigationGroupID=ng.NavigiationGroupIDGROUP BY YEAR(oh.CreationDate), MONTH(oh.CreationDate), ng.Description;