Table:
0
A
B
C
D
1
student id
detention id
incident id
students in detention
2
3
15
1
3
8
13
3
4
11
6
11
5
12
12
1
6
14
15
13
7
7
7
8
8
13
9
12
9
10
14
8
10
12
2
13
11
12
12
1
12
9
15
15
13
10
7
12
14
13
3
3
15
8
15
14
16
8
14
14

Questions and formulas:
Question: How many distinct students have been in detention?
Formula: SUMMARIZE(B1,DCOUNTX(A1))
Formula2: SUMMARIZE(B2:B16,DCOUNTX(A2:A16))
Level: easy