How Can I Add A Running Total Of One Column To An Access Query?

I have a query that contains in one field the percentage of total sales corresponding to a specific product in the past 12 months. For example: Product 1 - 38% Product 2 - 25% Prod

Solution 1:

If you have an ID field, or a date field, you can use a variation of this correlated subquery.

SELECT t.*,
     t.productpct+[prev_value] AS RunningSum,

 (select sum([ProductPct])            
 from test AS t2                   
  WHERE             
  t2.ID < t.ID  
 ) AS Prev_Value

FROM test AS t;

There are people who are way better at SQL than I, however if this helps or gives you your answer then great.