Thread: How to Return Moving Differences with Grouping?

Why do you want 2009-10-04 10 to be returned? That day has only one total-value. For the rest of the rows the following query returns the result you are asking for: SELECT date, MAX(total) - MIN(total) FROM tablename GROUP BY date Note that DATE is a reserved word in ANSI SQL. It's a good idea to avoid reserved words as column names. (Or do at least double quote them, i.e "DATE".)

I'm not even sure if that is the correct terminology, so let me start with some sample data. Say I have a table "data" with colums "id", "datetime", "total". Say the data looks something like ID DATE TOTAL 1 2009-10-01 00:00:00 10 2 2009-10-01 01:00:00 15 3 2009-10-01 02:00:00 17 4 2009-10-01 03:00:00 19 5 2009-10-01 04:00:00 21 6 2009-10-02 00:00:00 25 7 2009-10-02...