What is the average number of stars given by Oregon clients in their reviews?
average = DIVIDE(SUM(State = 'Oregon'), COUNT(district_id)); Oregon refers to state = 'Oregon';
SELECT CAST(SUM(T3.Stars) AS REAL) / COUNT(T3.Stars) AS average FROM state AS T1 INNER JOIN district AS T2 ON T1.StateCode = T2.state_abbrev INNER JOIN reviews AS T3 ON T2.district_id = T3.district_id WHERE T1.State = 'Oregon'