create table Stu ( i int, x float, y float ) insert into Stu values (1,3,9) insert into Stu values (2,2,7) insert into Stu values (3,4,12) insert into Stu values (4,5,15) insert into Stu values (5,6,17) select * from Stu select (1.0/n)*sum((x-xbar)*(y-ybar)) as Covariance from Stu, ( select count(*) as n, avg(x) as xbar, avg(y) as ybar from Stu ) A group by n go drop table Stu