I want to display Closing Stock Share and Tertiary Sales Share as a expressions column names,under these i want to show 4 expressions for each heading like Jan12,Dec11,Nov11,etc..but it is calculated expression names.
You can get the look you want using a pivot table. Set up the two heading rows in your examples as dimensions, and drag to the top of the table.
Its best if the dimensions are field names but if you cant load them in script, you can use calculated dimensions. If you need help with the calc dimensions, then you will need to be more specific about your requirements.
Logic will get you from a to b. Imagination will take you everywhere. - A Einstein