SQL Exercise: List the referees with their countries for each match
48. From the following table, write a SQL query to find the name of referees for each match. Sort the result-set on match number. Return match number, country name, referee name.
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
.........
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
.......
70018 | Clement Turpin | 1207
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
......
1229 | NOR | Norway
Sample Solution:
SQL Code:
-- Selecting match number, country name, and referee name for each match
SELECT
a.match_no, -- Selecting the match number from the match_mast table
b.country_name, -- Selecting the country name from the soccer_country table
c.referee_name -- Selecting the referee name from the referee_mast table
FROM
match_mast a -- Specifying the match_mast table with alias 'a'
JOIN
referee_mast c ON a.referee_id = c.referee_id -- Joining the match_mast table with the referee_mast table on the referee ID
JOIN
soccer_country b ON c.country_id = b.country_id -- Joining the referee_mast table with the soccer_country table on the country ID
-- Ordering the results by match number
ORDER BY
a.match_no;
Sample Output:
match_no | country_name | referee_name
----------+----------------+-------------------------
1 | Hungary | Viktor Kassai
2 | Spain | Carlos Velasco Carballo
3 | Norway | Svein Oddvar Moen
4 | Italy | Nicola Rizzoli
5 | Sweden | Jonas Eriksson
6 | Romania | Ovidiu Hategan
7 | England | Martin Atkinson
8 | Poland | Szymon Marciniak
9 | Serbia | Milorad Mazic
10 | England | Mark Clattenburg
11 | France | Clement Turpin
12 | Turkey | Cuneyt Cakir
13 | Slovenia | Damir Skomina
14 | Russia | Sergei Karasev
15 | Scotland | William Collum
16 | Germany | Felix Brych
17 | Czech Republic | Pavel Kralovec
18 | Netherlands | Bjorn Kuipers
19 | Hungary | Viktor Kassai
20 | England | Mark Clattenburg
21 | Serbia | Milorad Mazic
22 | Turkey | Cuneyt Cakir
23 | Russia | Sergei Karasev
24 | Italy | Nicola Rizzoli
25 | Czech Republic | Pavel Kralovec
26 | Slovenia | Damir Skomina
27 | Sweden | Jonas Eriksson
28 | Spain | Carlos Velasco Carballo
29 | Norway | Svein Oddvar Moen
30 | France | Clement Turpin
31 | Scotland | William Collum
32 | Netherlands | Bjorn Kuipers
33 | Poland | Szymon Marciniak
34 | England | Martin Atkinson
35 | Romania | Ovidiu Hategan
36 | Germany | Felix Brych
37 | England | Mark Clattenburg
38 | England | Martin Atkinson
39 | Spain | Carlos Velasco Carballo
40 | Italy | Nicola Rizzoli
41 | Poland | Szymon Marciniak
42 | Serbia | Milorad Mazic
43 | Turkey | Cuneyt Cakir
44 | Slovenia | Damir Skomina
45 | Germany | Felix Brych
46 | Slovenia | Damir Skomina
47 | Hungary | Viktor Kassai
48 | Netherlands | Bjorn Kuipers
49 | Sweden | Jonas Eriksson
50 | Italy | Nicola Rizzoli
51 | England | Mark Clattenburg
(51 rows)
Code Explanation:
The said query in SQL that selects the match number, country name, and referee name for each match in the match_mast table.
The JOIN clause in this query then joins the match_mast and referee_mast tables based on the referee_id column and joins the results with soccer_country tables based on the country_id column.
The query then orders the results by match number in ascending order using the ORDER BY clause.
Alternative Solution:
Correlated Subquery:
-- Selecting match number, country name, and referee name for each match
SELECT
a.match_no, -- Selecting the match number from the match_mast table
( -- Subquery to select the country name associated with the referee for each match
SELECT b.country_name -- Selecting the country name from the soccer_country table
FROM soccer_country b -- Specifying the soccer_country table with alias 'b'
JOIN referee_mast c ON b.country_id = c.country_id -- Joining the soccer_country table with the referee_mast table on the country ID
WHERE a.referee_id = c.referee_id -- Matching the referee ID with the one in the outer query
) AS country_name, -- Alias for the country name subquery result
( -- Subquery to select the referee name for each match
SELECT c.referee_name -- Selecting the referee name from the referee_mast table
FROM referee_mast c -- Specifying the referee_mast table with alias 'c'
WHERE a.referee_id = c.referee_id -- Matching the referee ID with the one in the outer query
) AS referee_name -- Alias for the referee name subquery result
FROM
match_mast a -- Specifying the match_mast table with alias 'a'
-- Ordering the results by match number
ORDER BY
a.match_no;
Explanation:
This query uses correlated subqueries to retrieve the country name and referee name based on the referee ID associated with each match. The outer query selects the match number.
Relational Algebra Expression:
Relational Algebra Tree:
Go to:
PREV : Countries where assistant referees assist most matches.
NEXT : The number of matches each referee has managed.
Practice Online
Sample Database: soccer
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