MySQL Query for Average of last 2 attempts

Question

I have a table:

quiz userid  attempt grade

1      3        1     33

2      3        1     67

1      3        2     90

10     3        4     20

2      3              


        

Answer 1

Selecting the last two rows = selecting the first two rows of a reversed set.

Simply order by attempt DESC (that makes it 4,3,2,1) and then grab the first two (4,3).

SELECT * FROM table WHERE <...> ORDER BY attempt DESC LIMIT 2