Which of the following are valid values for a boolean value in programming? (Select all that apply)

'f'
false
+
-
't'
true
0
1

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)?

Which of the following calculates the total from the adjacent cell through the first nonnumeric cell by default, using the sum function in its formula? -average -autosum -counta -max

Auniform resource locator (url) is a formatted string of text that web browsers, email applications, and other software programs use to identify a particular resource on the internet. true false