SQL Exercise: Find the yellow cards received by each country
17. From the following tables, write a SQL query to count the number of yellow cards each country has received. Return country name and number of yellow cards.
Sample table: soccer_country
country_id | country_abbr | country_name
------------+--------------+---------------------
1201 | ALB | Albania
1202 | AUT | Austria
1203 | BEL | Belgium
1204 | CRO | Croatia
1205 | CZE | Czech Republic
1206 | ENG | England
1207 | FRA | France
1208 | GER | Germany
1209 | HUN | Hungary
1210 | ISL | Iceland
1211 | ITA | Italy
1212 | NIR | Northern Ireland
1213 | POL | Poland
1214 | POR | Portugal
1215 | IRL | Republic of Ireland
1216 | ROU | Romania
1217 | RUS | Russia
1218 | SVK | Slovakia
1219 | ESP | Spain
1220 | SWE | Sweden
1221 | SUI | Switzerland
1222 | TUR | Turkey
1223 | UKR | Ukraine
1224 | WAL | Wales
1225 | SLO | Slovenia
1226 | NED | Netherlands
1227 | SRB | Serbia
1228 | SCO | Scotland
1229 | NOR | Norway
Sample table: player_booked
match_no | team_id | player_id | booking_time | sent_off | play_schedule | play_half
----------+---------+-----------+--------------+----------+---------------+-----------
1 | 1216 | 160349 | 32 | | NT | 1
1 | 1216 | 160355 | 45 | | NT | 1
1 | 1207 | 160159 | 69 | Y | NT | 2
1 | 1216 | 160360 | 78 | | NT | 2
2 | 1221 | 160470 | 14 | | NT | 1
2 | 1201 | 160013 | 23 | | NT | 1
2 | 1201 | 160013 | 36 | | NT | 1
2 | 1201 | 160014 | 63 | | NT | 2
2 | 1221 | 160472 | 66 | | NT | 2
2 | 1201 | 160015 | 89 | | NT | 2
2 | 1201 | 160009 | 93 | | NT | 2
3 | 1218 | 160401 | 2 | | ST | 2
3 | 1218 | 160406 | 31 | | NT | 1
3 | 1218 | 160408 | 78 | | NT | 2
3 | 1218 | 160411 | 80 | | NT | 2
3 | 1218 | 160407 | 83 | | NT | 2
4 | 1206 | 160120 | 62 | | NT | 2
4 | 1217 | 160377 | 72 | | NT | 2
5 | 1222 | 160505 | 31 | | NT | 1
5 | 1222 | 160490 | 48 | | NT | 2
5 | 1204 | 160077 | 80 | | NT | 2
5 | 1222 | 160502 | 91 | | NT | 2
6 | 1213 | 160290 | 65 | | NT | 2
6 | 1212 | 160258 | 69 | | NT | 2
6 | 1213 | 160284 | 89 | | NT | 2
7 | 1223 | 160518 | 68 | | NT | 2
8 | 1205 | 160100 | 61 | | NT | 2
9 | 1215 | 160336 | 43 | | NT | 1
9 | 1220 | 160445 | 61 | | NT | 2
9 | 1215 | 160341 | 77 | | NT | 2
10 | 1211 | 160236 | 65 | | NT | 2
10 | 1211 | 160248 | 75 | | NT | 2
10 | 1211 | 160235 | 78 | | NT | 2
10 | 1211 | 160245 | 84 | | NT | 2
10 | 1203 | 160057 | 93 | | NT | 2
11 | 1202 | 160027 | 33 | | NT | 1
11 | 1202 | 160027 | 66 | Y | NT | 2
11 | 1209 | 160204 | 80 | | NT | 2
12 | 1210 | 160227 | 2 | | ST | 2
12 | 1210 | 160221 | 55 | | NT | 2
13 | 1218 | 160395 | 46 | | NT | 2
14 | 1221 | 160480 | 2 | | ST | 2
14 | 1216 | 160361 | 22 | | NT | 1
14 | 1216 | 160357 | 24 | | NT | 1
14 | 1216 | 160367 | 37 | | NT | 1
14 | 1221 | 160477 | 50 | | NT | 2
14 | 1216 | 160352 | 76 | | NT | 2
15 | 1201 | 160015 | 55 | | NT | 2
15 | 1201 | 160011 | 81 | | NT | 2
15 | 1207 | 160152 | 88 | | NT | 2
16 | 1224 | 160535 | 61 | | NT | 2
17 | 1223 | 160528 | 40 | | NT | 1
17 | 1212 | 160272 | 63 | | NT | 2
17 | 1223 | 160523 | 67 | | NT | 2
17 | 1212 | 160266 | 87 | | NT | 2
17 | 1212 | 160259 | 90 | | NT | 2
18 | 1208 | 160175 | 3 | | NT | 1
18 | 1213 | 160294 | 3 | | ST | 2
18 | 1208 | 160177 | 34 | | NT | 1
18 | 1213 | 160293 | 45 | | NT | 1
18 | 1213 | 160288 | 55 | | NT | 2
18 | 1208 | 160165 | 67 | | NT | 2
19 | 1211 | 160242 | 69 | | NT | 2
19 | 1220 | 160447 | 89 | | NT | 2
19 | 1211 | 160231 | 94 | | NT | 2
20 | 1204 | 160080 | 14 | | NT | 1
20 | 1205 | 160101 | 72 | | NT | 2
20 | 1204 | 160081 | 74 | | NT | 2
20 | 1204 | 160078 | 88 | | NT | 2
21 | 1219 | 160424 | 2 | | NT | 1
21 | 1222 | 160504 | 9 | | NT | 1
21 | 1222 | 160500 | 41 | | NT | 1
22 | 1215 | 160334 | 42 | | NT | 1
22 | 1203 | 160056 | 49 | | NT | 2
23 | 1209 | 160199 | 2 | | ST | 2
23 | 1210 | 160229 | 42 | | NT | 1
23 | 1210 | 160227 | 75 | | NT | 2
23 | 1210 | 160216 | 77 | | NT | 2
23 | 1209 | 160192 | 81 | | NT | 2
23 | 1209 | 160197 | 83 | | NT | 2
24 | 1202 | 160028 | 6 | | NT | 1
24 | 1214 | 160321 | 31 | | NT | 1
24 | 1214 | 160307 | 40 | | NT | 1
24 | 1202 | 160037 | 47 | | NT | 2
24 | 1202 | 160029 | 78 | | NT | 2
24 | 1202 | 160042 | 86 | | NT | 2
25 | 1201 | 160012 | 6 | | NT | 1
25 | 1216 | 160353 | 54 | | NT | 2
25 | 1201 | 160017 | 85 | | NT | 2
25 | 1216 | 160356 | 85 | | NT | 2
25 | 1216 | 160364 | 91 | | NT | 2
25 | 1201 | 160007 | 95 | | NT | 2
26 | 1207 | 160147 | 25 | | NT | 1
26 | 1207 | 160145 | 83 | | NT | 2
27 | 1224 | 160551 | 16 | | NT | 1
27 | 1217 | 160383 | 64 | | NT | 2
28 | 1218 | 160409 | 24 | | NT | 1
28 | 1206 | 160119 | 52 | | NT | 2
29 | 1223 | 160520 | 25 | | NT | 1
29 | 1223 | 160513 | 38 | | NT | 1
29 | 1213 | 160290 | 60 | | NT | 2
31 | 1222 | 160491 | 35 | | NT | 1
31 | 1205 | 160108 | 36 | | NT | 1
31 | 1205 | 160107 | 39 | Y | NT | 1
31 | 1222 | 160490 | 50 | | NT | 2
31 | 1205 | 160112 | 87 | | NT | 2
32 | 1204 | 160087 | 29 | | NT | 1
32 | 1204 | 160079 | 70 | | NT | 2
32 | 1204 | 160076 | 70 | | NT | 2
32 | 1204 | 160085 | 88 | | NT | 2
33 | 1210 | 160218 | 36 | | NT | 1
33 | 1210 | 160230 | 51 | | NT | 2
33 | 1202 | 160045 | 70 | | NT | 2
33 | 1210 | 160220 | 78 | | NT | 2
33 | 1210 | 160208 | 82 | | NT | 2
34 | 1209 | 160190 | 13 | | NT | 1
34 | 1209 | 160191 | 28 | | NT | 1
34 | 1209 | 160203 | 34 | | NT | 1
34 | 1209 | 160202 | 56 | | NT | 2
35 | 1211 | 160233 | 39 | | NT | 1
35 | 1215 | 160343 | 39 | | NT | 1
35 | 1215 | 160332 | 73 | | NT | 2
35 | 1211 | 160234 | 78 | | NT | 2
35 | 1211 | 160253 | 87 | | NT | 2
35 | 1211 | 160251 | 93 | | NT | 2
36 | 1203 | 160064 | 1 | | ST | 1
36 | 1203 | 160055 | 30 | | NT | 1
36 | 1220 | 160451 | 72 | | NT | 2
37 | 1221 | 160470 | 55 | | NT | 2
37 | 1213 | 160282 | 58 | | NT | 2
38 | 1212 | 160266 | 44 | | NT | 1
38 | 1224 | 160538 | 58 | | NT | 2
38 | 1212 | 160267 | 67 | | NT | 2
38 | 1224 | 160544 | 92 | | NT | 2
39 | 1214 | 160318 | 78 | | NT | 2
40 | 1215 | 160328 | 25 | | NT | 1
40 | 1207 | 160152 | 27 | | NT | 1
40 | 1215 | 160334 | 41 | | NT | 1
40 | 1207 | 160147 | 44 | | NT | 1
40 | 1215 | 160329 | 66 | Y | NT | 2
40 | 1215 | 160343 | 72 | | NT | 2
41 | 1218 | 160407 | 2 | | ST | 2
41 | 1218 | 160401 | 13 | | NT | 1
41 | 1208 | 160169 | 46 | | NT | 2
41 | 1208 | 160168 | 67 | | NT | 2
42 | 1209 | 160192 | 34 | | NT | 1
42 | 1209 | 160194 | 47 | | NT | 2
42 | 1209 | 160196 | 61 | | NT | 2
42 | 1203 | 160056 | 67 | | NT | 2
42 | 1203 | 160065 | 89 | | NT | 2
42 | 1203 | 160061 | 91 | | NT | 2
42 | 1209 | 160207 | 92 | | NT | 2
43 | 1219 | 160431 | 2 | | ST | 2
43 | 1211 | 160238 | 24 | | NT | 1
43 | 1219 | 160436 | 41 | | NT | 1
43 | 1211 | 160252 | 54 | | NT | 2
43 | 1211 | 160245 | 89 | | NT | 2
43 | 1219 | 160427 | 89 | | NT | 2
43 | 1219 | 160421 | 89 | | NT | 2
44 | 1210 | 160208 | 38 | | NT | 1
44 | 1206 | 160137 | 47 | | NT | 2
44 | 1210 | 160222 | 65 | | NT | 2
45 | 1214 | 160318 | 2 | | ST | 2
45 | 1213 | 160282 | 42 | | NT | 1
45 | 1213 | 160281 | 66 | | NT | 2
45 | 1214 | 160310 | 70 | | NT | 2
45 | 1213 | 160290 | 89 | | NT | 2
46 | 1224 | 160535 | 5 | | NT | 1
46 | 1224 | 160533 | 16 | | NT | 1
46 | 1224 | 160536 | 24 | | NT | 1
46 | 1203 | 160061 | 59 | | NT | 2
46 | 1224 | 160544 | 75 | | NT | 2
46 | 1203 | 160050 | 85 | | NT | 2
47 | 1211 | 160247 | 56 | | NT | 2
47 | 1211 | 160238 | 57 | | NT | 2
47 | 1211 | 160246 | 59 | | NT | 2
47 | 1208 | 160168 | 90 | | NT | 2
47 | 1208 | 160180 | 112 | | NT | 2
48 | 1210 | 160221 | 58 | | NT | 2
48 | 1207 | 160149 | 75 | | NT | 2
49 | 1224 | 160540 | 8 | | NT | 1
49 | 1224 | 160533 | 62 | | NT | 2
49 | 1214 | 160303 | 71 | | NT | 2
49 | 1214 | 160322 | 72 | | NT | 2
49 | 1224 | 160547 | 88 | | NT | 2
50 | 1208 | 160177 | 1 | | ST | 1
50 | 1208 | 160172 | 36 | | NT | 1
50 | 1207 | 160143 | 43 | | NT | 1
50 | 1208 | 160180 | 45 | | NT | 1
50 | 1208 | 160173 | 50 | | NT | 2
50 | 1207 | 160152 | 75 | | NT | 2
51 | 1214 | 160304 | 34 | | NT | 1
51 | 1214 | 160313 | 62 | | NT | 2
51 | 1207 | 160149 | 80 | | NT | 2
51 | 1214 | 160308 | 95 | | ET | 1
51 | 1207 | 160153 | 97 | | ET | 1
51 | 1214 | 160318 | 98 | | ET | 1
51 | 1207 | 160145 | 107 | | ET | 2
51 | 1207 | 160155 | 115 | | ET | 2
51 | 1214 | 160306 | 119 | | ET | 2
51 | 1214 | 160302 | 122 | | ET | 2
Sample Solution:
SQL Code:
-- Selecting country_name and the count of booked players for each country
SELECT country_name, COUNT(*)
-- From clause with JOIN between soccer_country and player_booked
FROM soccer_country
JOIN player_booked
-- Joining soccer_country and player_booked based on country_id and team_id
ON soccer_country.country_id = player_booked.team_id
-- Grouping the results by country_name to count booked players for each country
GROUP BY country_name
-- Ordering the results by the count of booked players in descending order
ORDER BY COUNT(*) DESC;
Sample Output:
country_name | count
---------------------+-------
Italy | 16
France | 13
Portugal | 13
Hungary | 12
Iceland | 12
Wales | 11
Germany | 11
Romania | 10
Albania | 10
Poland | 10
Republic of Ireland | 9
Slovakia | 9
Belgium | 9
Croatia | 8
Turkey | 7
Austria | 7
Northern Ireland | 6
Czech Republic | 5
Spain | 5
Ukraine | 5
Switzerland | 5
England | 3
Sweden | 3
Russia | 2
(24 rows)
Code Explanation:
The said query in SQL that selects a list of all countries along with the count of player bookings for each country from the tables 'soccer_country' and 'player_booked'.
The JOIN keyword with ON clause is used to specify the join condition where the country ID from the 'soccer_country' table matches the team ID from the 'player_booked' table.
The GROUP BY clause groups the results by country name. This means that the COUNT(*) function will count the number of player bookings for each country.
The query is using the ORDER BY clause to sort the results in descending order based on the count of player bookings.
Alternative Solutions:
Using a Subquery:
-- Selecting all columns from a subquery that counts booked players for each country
SELECT *
-- From clause with a subquery (aliased as subquery)
FROM (
-- Subquery to select country_name and the count of booked players for each country
SELECT country_name,
-- Subquery to count booked players for each country based on team_id
(SELECT COUNT(*)
FROM player_booked
WHERE player_booked.team_id = soccer_country.country_id
) as booking_count
-- From clause with the main query selecting country_name from soccer_country
FROM soccer_country
) AS subquery
-- Where clause to filter results where booking_count is greater than 0
WHERE booking_count > 0
-- Ordering the results by booking_count in descending order
ORDER BY booking_count DESC;
Explanation:
This query uses a subquery in the SELECT clause to calculate the count of bookings for each country. The subquery correlates with the outer query using the team_id, and the result is selected alongside the country_name.
Using LEFT JOIN:
-- Selecting country_name and booking_count from a subquery that counts booked players for each country
SELECT country_name, booking_count
-- From clause with a subquery (aliased as subquery)
FROM (
-- Subquery to select country_name and the count of booked players for each country
SELECT country_name, COUNT(player_booked.team_id) as booking_count
-- From clause with LEFT JOIN between soccer_country and player_booked based on country_id and team_id
FROM soccer_country
LEFT JOIN player_booked ON soccer_country.country_id = player_booked.team_id
-- Grouping the results by country_name to count booked players for each country
GROUP BY country_name
) AS subquery
-- Where clause to filter results where booking_count is greater than 0
WHERE booking_count > 0
-- Ordering the results by booking_count in descending order
ORDER BY booking_count DESC;
Explanation:
This query creates a subquery where booking_count is calculated, and then filters the results in the outer query to only include rows where booking_count is greater than 0. This should give you the desired result.
Relational Algebra Expression:
Relational Algebra Tree:
Practice Online
Sample Database: soccer
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