I have table with age values in column 1 and weight values in the remaining columns indicating the weight centiles for a given age, simplified: age,c10,c25,c50,c75,c90 ----------------------- 1,5,6,7,8,9 2,6,7,8,9,10 3,7,8,9,10,11 So, for example age 3, weight 9 then that would give c50 (50th centile, that is average weight for that age). How would I do that in SQL, so giving me c50 for values age 3 and weight 9? RBS