SQL Exercise: Find the referees who booked most number of players
55. From the following tables, write a SQL query to find those referees who booked the most number of players. Return referee name, number of matches.
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 table: match_mast
match_no | play_stage | play_date | results | decided_by | goal_score | venue_id | referee_id | audence | plr_of_match | stop1_sec | stop2_sec
----------+------------+------------+---------+------------+------------+----------+------------+---------+--------------+-----------+-----------
1 | G | 2016-06-11 | WIN | N | 2-1 | 20008 | 70007 | 75113 | 160154 | 131 | 242
2 | G | 2016-06-11 | WIN | N | 0-1 | 20002 | 70012 | 33805 | 160476 | 61 | 182
3 | G | 2016-06-11 | WIN | N | 2-1 | 20001 | 70017 | 37831 | 160540 | 64 | 268
4 | G | 2016-06-12 | DRAW | N | 1-1 | 20005 | 70011 | 62343 | 160128 | 0 | 185
5 | G | 2016-06-12 | WIN | N | 0-1 | 20007 | 70006 | 43842 | 160084 | 125 | 325
6 | G | 2016-06-12 | WIN | N | 1-0 | 20006 | 70014 | 33742 | 160291 | 2 | 246
7 | G | 2016-06-13 | WIN | N | 2-0 | 20003 | 70002 | 43035 | 160176 | 89 | 188
8 | G | 2016-06-13 | WIN | N | 1-0 | 20010 | 70009 | 29400 | 160429 | 360 | 182
9 | G | 2016-06-13 | DRAW | N | 1-1 | 20008 | 70010 | 73419 | 160335 | 67 | 194
10 | G | 2016-06-14 | WIN | N | 0-2 | 20004 | 70005 | 55408 | 160244 | 63 | 189
11 | G | 2016-06-14 | WIN | N | 0-2 | 20001 | 70018 | 34424 | 160197 | 61 | 305
12 | G | 2016-06-15 | DRAW | N | 1-1 | 20009 | 70004 | 38742 | 160320 | 15 | 284
13 | G | 2016-06-15 | WIN | N | 1-2 | 20003 | 70001 | 38989 | 160405 | 62 | 189
14 | G | 2016-06-15 | DRAW | N | 1-1 | 20007 | 70015 | 43576 | 160477 | 74 | 206
15 | G | 2016-06-16 | WIN | N | 2-0 | 20005 | 70013 | 63670 | 160154 | 71 | 374
16 | G | 2016-06-16 | WIN | N | 2-1 | 20002 | 70003 | 34033 | 160540 | 62 | 212
17 | G | 2016-06-16 | WIN | N | 0-2 | 20004 | 70016 | 51043 | 160262 | 7 | 411
18 | G | 2016-06-17 | DRAW | N | 0-0 | 20008 | 70008 | 73648 | 160165 | 6 | 208
19 | G | 2016-06-17 | WIN | N | 1-0 | 20010 | 70007 | 29600 | 160248 | 2 | 264
20 | G | 2016-06-17 | DRAW | N | 2-2 | 20009 | 70005 | 38376 | 160086 | 71 | 280
21 | G | 2016-06-18 | WIN | N | 3-0 | 20006 | 70010 | 33409 | 160429 | 84 | 120
22 | G | 2016-06-18 | WIN | N | 3-0 | 20001 | 70004 | 39493 | 160064 | 11 | 180
23 | G | 2016-06-18 | DRAW | N | 1-1 | 20005 | 70015 | 60842 | 160230 | 61 | 280
24 | G | 2016-06-19 | DRAW | N | 0-0 | 20007 | 70011 | 44291 | 160314 | 3 | 200
25 | G | 2016-06-20 | WIN | N | 0-1 | 20004 | 70016 | 49752 | 160005 | 125 | 328
26 | G | 2016-06-20 | DRAW | N | 0-0 | 20003 | 70001 | 45616 | 160463 | 60 | 122
27 | G | 2016-06-21 | WIN | N | 0-3 | 20010 | 70006 | 28840 | 160544 | 62 | 119
28 | G | 2016-06-21 | DRAW | N | 0-0 | 20009 | 70012 | 39051 | 160392 | 62 | 301
29 | G | 2016-06-21 | WIN | N | 0-1 | 20005 | 70017 | 58874 | 160520 | 29 | 244
30 | G | 2016-06-21 | WIN | N | 0-1 | 20007 | 70018 | 44125 | 160177 | 21 | 195
31 | G | 2016-06-22 | WIN | N | 0-2 | 20002 | 70013 | 32836 | 160504 | 60 | 300
32 | G | 2016-06-22 | WIN | N | 2-1 | 20001 | 70008 | 37245 | 160085 | 70 | 282
33 | G | 2016-06-22 | WIN | N | 2-1 | 20008 | 70009 | 68714 | 160220 | 7 | 244
34 | G | 2016-06-22 | DRAW | N | 3-3 | 20004 | 70002 | 55514 | 160322 | 70 | 185
35 | G | 2016-06-23 | WIN | N | 0-1 | 20003 | 70014 | 44268 | 160333 | 79 | 221
36 | G | 2016-06-23 | WIN | N | 0-1 | 20006 | 70003 | 34011 | 160062 | 63 | 195
37 | R | 2016-06-25 | WIN | P | 1-1 | 20009 | 70005 | 38842 | 160476 | 126 | 243
38 | R | 2016-06-25 | WIN | N | 1-0 | 20007 | 70002 | 44342 | 160547 | 5 | 245
39 | R | 2016-06-26 | WIN | N | 0-1 | 20002 | 70012 | 33523 | 160316 | 61 | 198
40 | R | 2016-06-26 | WIN | N | 2-1 | 20004 | 70011 | 56279 | 160160 | 238 | 203
41 | R | 2016-06-26 | WIN | N | 3-0 | 20003 | 70009 | 44312 | 160173 | 62 | 124
42 | R | 2016-06-27 | WIN | N | 0-4 | 20010 | 70010 | 28921 | 160062 | 3 | 133
43 | R | 2016-06-27 | WIN | N | 2-0 | 20008 | 70004 | 76165 | 160235 | 63 | 243
44 | R | 2016-06-28 | WIN | N | 1-2 | 20006 | 70001 | 33901 | 160217 | 5 | 199
45 | Q | 2016-07-01 | WIN | P | 1-1 | 20005 | 70003 | 62940 | 160316 | 58 | 181
46 | Q | 2016-07-02 | WIN | N | 3-1 | 20003 | 70001 | 45936 | 160550 | 14 | 182
47 | Q | 2016-07-03 | WIN | P | 1-1 | 20001 | 70007 | 38764 | 160163 | 63 | 181
48 | Q | 2016-07-04 | WIN | N | 5-2 | 20008 | 70008 | 76833 | 160159 | 16 | 125
49 | S | 2016-07-07 | WIN | N | 2-0 | 20004 | 70006 | 55679 | 160322 | 2 | 181
50 | S | 2016-07-08 | WIN | N | 2-0 | 20005 | 70011 | 64078 | 160160 | 126 | 275
51 | F | 2016-07-11 | WIN | N | 1-0 | 20008 | 70005 | 75868 | 160307 | 161 | 181
Sample table: referee_mast
referee_id | referee_name | country_id
------------+-------------------------+------------
70001 | Damir Skomina | 1225
70002 | Martin Atkinson | 1206
70003 | Felix Brych | 1208
70004 | Cuneyt Cakir | 1222
70005 | Mark Clattenburg | 1206
70006 | Jonas Eriksson | 1220
70007 | Viktor Kassai | 1209
70008 | Bjorn Kuipers | 1226
70009 | Szymon Marciniak | 1213
70010 | Milorad Mazic | 1227
70011 | Nicola Rizzoli | 1211
70012 | Carlos Velasco Carballo | 1219
70013 | William Collum | 1228
70014 | Ovidiu Hategan | 1216
70015 | Sergei Karasev | 1217
70016 | Pavel Kralovec | 1205
70017 | Svein Oddvar Moen | 1229
70018 | Clement Turpin | 1207
Sample Solution:
SQL Code:
-- Selecting the referee name and the count of matches where bookings occurred for each referee
SELECT
c.referee_name, -- Selecting the referee name
COUNT(b.match_no) -- Counting the number of matches for each referee
FROM
player_booked a -- Selecting from the player_booked table with alias 'a'
JOIN
match_mast b ON a.match_no = b.match_no -- Joining with the match_mast table with alias 'b' based on match number
JOIN
referee_mast c ON b.referee_id = c.referee_id -- Joining with the referee_mast table with alias 'c' based on referee ID
GROUP BY
referee_name -- Grouping the results by referee name
HAVING
COUNT(b.match_no) = (
SELECT
MAX(mm) -- Selecting the maximum count of matches for any referee
FROM
(
SELECT
COUNT(b.match_no) AS mm -- Counting the matches for each referee
FROM
player_booked a
JOIN
match_mast b ON a.match_no = b.match_no
JOIN
referee_mast c ON b.referee_id = c.referee_id
GROUP BY
referee_name
) hh
);
Sample Output:
referee_name | count ------------------+------- Mark Clattenburg | 21 (1 row)
Code Explanation:
The provided query in SQL query that retrieves player_booked table aliased as a, match_mast table aliased as b, and referee_mast table aliased as c and returns the name of the referee(s) who received the maximum number of bookings.
The JOIN keyword joins the player_booked and match_mast tables based on the match_no column, the match_mast and the referee_mast tables based on the referee_id column.
The GROUP BY statement groups the results by referee_name.
The HAVING clause filters the results to only include referees who received the maximum number of bookings.
The subquery within the HAVING clause selects the maximum number of bookings from the group of referees.
The query returns the name(s) of the referee(s) who received the maximum number of bookings.
Alternative Solutions:
Using a Window Function:
-- Selecting the referee name and the count of matches where bookings occurred for the top-ranking referee
SELECT
referee_name, -- Selecting the referee name
match_count -- Selecting the count of matches where bookings occurred
FROM
(
-- Subquery to calculate the count of matches and rank each referee based on the count of matches
SELECT
c.referee_name, -- Selecting the referee name
COUNT(b.match_no) AS match_count, -- Counting the number of matches for each referee
RANK() OVER (ORDER BY COUNT(b.match_no) DESC) AS rank -- Ranking the referees based on the count of matches
FROM
player_booked a -- Selecting from the player_booked table with alias 'a'
JOIN
match_mast b ON a.match_no = b.match_no -- Joining with the match_mast table with alias 'b' based on match number
JOIN
referee_mast c ON b.referee_id = c.referee_id -- Joining with the referee_mast table with alias 'c' based on referee ID
GROUP BY
c.referee_name -- Grouping the results by referee name
) ranked
-- Selecting the top-ranking referee
WHERE
rank = 1;
Explanation:
This query uses a window function RANK() to assign a rank to each referee based on the count of matches. It then selects the referee with rank 1, which corresponds to the highest match count.
Using a Scalar Subquery in SELECT Clause:
-- Selecting the referee name and the count of matches where bookings occurred for the top-ranking referee
SELECT
referee_name, -- Selecting the referee name
(SELECT COUNT(b.match_no) -- Subquery to count the number of matches where bookings occurred for the current referee
FROM player_booked a -- Selecting from the player_booked table with alias 'a'
JOIN match_mast b ON a.match_no = b.match_no -- Joining with the match_mast table with alias 'b' based on match number
JOIN referee_mast c ON b.referee_id = c.referee_id -- Joining with the referee_mast table with alias 'c' based on referee ID
WHERE c.referee_name = ranked.referee_name -- Filtering by the current referee name
) AS match_count -- Alias for the count of matches where bookings occurred
FROM
(
-- Subquery to calculate the count of matches and rank each referee based on the count of matches
SELECT
c.referee_name, -- Selecting the referee name
COUNT(b.match_no) AS match_count, -- Counting the number of matches for each referee
RANK() OVER (ORDER BY COUNT(b.match_no) DESC) AS rank -- Ranking the referees based on the count of matches
FROM
player_booked a -- Selecting from the player_booked table with alias 'a'
JOIN
match_mast b ON a.match_no = b.match_no -- Joining with the match_mast table with alias 'b' based on match number
JOIN
referee_mast c ON b.referee_id = c.referee_id -- Joining with the referee_mast table with alias 'c' based on referee ID
GROUP BY
c.referee_name -- Grouping the results by referee name
) ranked
-- Selecting the top-ranking referee
WHERE
rank = 1;
Explanation:
This query uses a scalar subquery in the SELECT clause to calculate the match count for each referee. It correlates the subquery with the main query using the referee name and then selects the referee with the highest match count.
Practice Online
Sample Database: soccer
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