Calculate percent increase/decrease from previous row value

Question

I have a table that looks something like this:

|date_start  | date_end    |amount | 
+------------+-------------+-------+
|2015-02-23  | 2015-03-01  |50              


        

Answer 1

Try this:

 SELECT t.*,
 amount - (SELECT amount FROM transactions prev WHERE prev.date_end     < t.date_start ORDER BY date_start DESC LIMIT 1) AS changes
 FROM   transactions t