When multiple columns in a query are sorted simultaneously, which one will be the primary sort? the primary key column
the middle column
the rightmost column
the leftmost column

THE ANSWER IS D

Awell-diversified portfolio needs about 20-25 stocks from different categories.

The north and south regions had very diferent economies in the 1800s.

Suppose there is a relation r(a, b, c) with a b+-tree index with search keys (a, b).1. what is the worst-case cost of finding records satisfying 10 < a < 50 using this index, in terms of the number of records n1, retrieved and the height h of the tree? 2. what is the worst-case cost of finding records satisfying 10 < a < 50 and 5 < b < 10 using this index, in terms of the number of records n2 that satisfy this selection, as well as n1 and h defined above? 3. under what conditions on n1 and n2, would the index be an efficient way of finding records satisfying the condition from part (2)?