Take the tour ×  Firstly apologies if this is a duplicate, I am
fairly new to SQL and so Im not sure what the correct
terminology to use in my searches  So I have a database which
records motor races, with the following simplified schema
race_id PK race_date timestamp average_speed Decimal max_speed
Decimal  driver_id PK driver_name text date_started timestamp
driver_id FK race_id FK  If each driver has ~1000 races spread
over 2/3 years  How would I go about querying the overall %
change (positive of negative) in their average race speed for a
given date range, for example  % Change in first 6 months  Joe
Smith - 5% increase Andy James - 4% increase  % Change in first
12 months  Joe Smith - 8% increase Lewis May - 6% increase
UPDATE: More detail on % Change  The % Change could be
calculated using linear regression, (least-squares-fit would be
suitable), the average change is effectivly the y-difference on
a line-of-best-fit, where each point is a race, x is the
race_date and y is the average_speed for that