Народ, только начал учить Oracle SQL, не могу решить две задачки никак для демобазы. Спасибо всем, кто поможет.

1. Print out salary grade, number in that grade and average salary within the grade, but only fot those grades with a total salary exceeding $3500.
2. Show the highest and lowest compensation (sal plus commission) in each salary grade. Remember, some employee have no comissions.