Derived/calculated column on existing table

Question

I have been going nuts over this issue for some time and I am seeking help.

I have SQL Server table with values, as follows:

Account - Date - Amount - Su         


        

Answer 1

Why are you duplicating this summary and previous year summary data for each row in your database? This is wasteful and unnecessary. It would be far better to have another table with previous year summaries, one row per year, that you could join to this table. And, I don't see a need for a Summary column at all. Why not create a view that calculates a Summary, when the month is 12, and returns a zero for any month not equal to 12.