Table:
0
A
B
C
D
E
F
1
airport id
city
country
iata
icao
name
2
1
Akureyri
Iceland
AEY
BIAR
Akureyri Airport
3
2
Amsterdam
Netherlands
AMS
EHAM
Schiphol Airport
4
3
Anchorage
United States
ANC
PANC
Ted Stevens Airport
5
4
Baltimore
United States
BWI
KBWI
Baltimore-Washington Airport
6
5
Barcelona
Spain
BCN
LEBL
El Prat Airport
7
6
Bergen
Norway
BGO
ENBR
Bergen Airport
8
7
Billund
Denmark
BLL
EKBI
Billund Airport
9
8
Boston
United States
BOS
KBOS
Logan International Airport
10
9
Brussels
Belgium
BRU
EBBR
National Airport

Questions and formulas:
Question: List the id, country, city and name of the airports ordered alphabetically by the name.
Formula: SORTBY(CHOOSE({1,2,3,4},A1,C1,B1,F1),F1,1)
Formula2: SORTBY(CHOOSE({1,2,3,4},A2:A10,C2:C10,B2:B10,F2:F10),F2:F10,1)
Level: easy
Question: What are the names of the airports which are not in the country 'Iceland'?
Formula: FILTER(F1,C1<>"Iceland")
Formula2: FILTER(F2:F10,C2:C10<>"Iceland")
Level: easy
Question: how many airports are there in each country?
Formula: SUMMARIZE(C1,SUMX(A1))
Formula2: SUMMARIZE(C2:C10,SUMX(A2:A10))
Level: easy
Question: which countries have more than 2 airports?
Formula: LET(query1,SUMMARIZE(C1,SUMX(A1)),FILTER(query1,CHOOSECOLS(query1,3)>2))
Formula2: LET(query1,SUMMARIZE(C2:C10,SUMX(A2:A10)),FILTER(query1,CHOOSECOLS(query1,3)>2))
Level: hard
Question: The airport names from a to z and their ids, cities and countries. 
Formula: SORT(UNIQUE(HSTACK(A1,C1,B1,F1)), 4, 1)
Formula2: SORT(UNIQUE(HSTACK(A2:A10,C2:C10,B2:B10,F2:F10)), 4, 1)
Level: medium
Question: Names and ids for all countries airports but Iceland. 
Formula: LET(query1,FILTER(A1:F1,C1<>"iceland"),UNIQUE(CHOOSECOLS(query1,6,1)))
Formula2: LET(query1,FILTER(A2:F10,C2:C10<>"iceland"),UNIQUE(CHOOSECOLS(query1,6,1)))
Level: hard
Question: How many airports does each country have?
Formula: SUMMARIZE(C1,SUMX(A1))
Formula2: SUMMARIZE(C2:C10,SUMX(A2:A10))
Level: easy
Question: Countries with more than 2 airports. 
Formula: LET(query1,SUMMARIZE(C1,SUMX(A1)),FILTER(query1,CHOOSECOLS(query1,3)>2))
Formula2: LET(query1,SUMMARIZE(C2:C10,SUMX(A2:A10)),FILTER(query1,CHOOSECOLS(query1,3)>2))
Level: hard
Question: Names and ids for all countries' airports excluding iceland.
Formula: LET(query1,FILTER(A1:F1,C1<>"iceland"),UNIQUE(CHOOSECOLS(query1,1,6,3)))
Formula2: LET(query1,FILTER(A2:F10,C2:C10<>"iceland"),UNIQUE(CHOOSECOLS(query1,1,6,3)))
Level: hard
Question: What is the number of airports in different countries?
Formula: SUMMARIZE(C1,DCOUNTX(A1))
Formula2: SUMMARIZE(C2:C10,DCOUNTX(A2:A10))
Level: easy
Question: The country having over 2 airports.
Formula: LET(query1,SUMMARIZE(C1,SUMX(A1)),FILTER(query1,CHOOSECOLS(query1,3)>2))
Formula2: LET(query1,SUMMARIZE(C2:C10,SUMX(A2:A10)),FILTER(query1,CHOOSECOLS(query1,3)>2))
Level: hard