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SQL Exercise: Referee who assisted in the opening match

SQL soccer Database: Joins Exercise-10 with Solution

10. From the following tables, write a SQL query to find the referee who assisted the referee in the opening match. Return associated referee name, country name.

Sample table: asst_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 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: match_details
 match_no | play_stage | team_id | win_lose | decided_by | goal_score | penalty_score | ass_ref | player_gk
----------+------------+---------+----------+------------+------------+---------------+---------+-----------
        1 | G          |    1207 | W        | N          |          2 |               |   80016 |    160140
        1 | G          |    1216 | L        | N          |          1 |               |   80020 |    160348
        2 | G          |    1201 | L        | N          |          0 |               |   80003 |    160001
        2 | G          |    1221 | W        | N          |          1 |               |   80023 |    160463
        3 | G          |    1224 | W        | N          |          2 |               |   80031 |    160532
        3 | G          |    1218 | L        | N          |          1 |               |   80025 |    160392
        4 | G          |    1206 | D        | N          |          1 |               |   80008 |    160117
        4 | G          |    1217 | D        | N          |          1 |               |   80019 |    160369
        5 | G          |    1222 | L        | N          |          0 |               |   80011 |    160486
        5 | G          |    1204 | W        | N          |          1 |               |   80022 |    160071
        6 | G          |    1213 | W        | N          |          1 |               |   80036 |    160279
        6 | G          |    1212 | L        | N          |          0 |               |   80029 |    160256
        7 | G          |    1208 | W        | N          |          2 |               |   80014 |    160163
        7 | G          |    1223 | L        | N          |          0 |               |   80006 |    160508
        8 | G          |    1219 | W        | N          |          1 |               |   80018 |    160416
        8 | G          |    1205 | L        | N          |          0 |               |   80012 |    160093
        9 | G          |    1215 | D        | N          |          1 |               |   80017 |    160324
        9 | G          |    1220 | D        | N          |          1 |               |   80010 |    160439
       10 | G          |    1203 | L        | N          |          0 |               |   80004 |    160047
       10 | G          |    1211 | W        | N          |          2 |               |   80007 |    160231
       11 | G          |    1202 | L        | N          |          0 |               |   80026 |    160024
       11 | G          |    1209 | W        | N          |          2 |               |   80028 |    160187
       12 | G          |    1214 | D        | N          |          1 |               |   80009 |    160302
       12 | G          |    1210 | D        | N          |          1 |               |   80015 |    160208
       13 | G          |    1217 | L        | N          |          1 |               |   80001 |    160369
       13 | G          |    1218 | W        | N          |          2 |               |   80002 |    160392
       14 | G          |    1216 | D        | N          |          1 |               |   80030 |    160348
       14 | G          |    1221 | D        | N          |          1 |               |   80032 |    160463
       15 | G          |    1207 | W        | N          |          2 |               |   80033 |    160140
       15 | G          |    1201 | L        | N          |          0 |               |   80027 |    160001
       16 | G          |    1206 | W        | N          |          2 |               |   80005 |    160117
       16 | G          |    1224 | L        | N          |          1 |               |   80013 |    160531
       17 | G          |    1223 | L        | N          |          0 |               |   80035 |    160508
       17 | G          |    1212 | W        | N          |          2 |               |   80034 |    160256
       18 | G          |    1208 | D        | N          |          0 |               |   80021 |    160163
       18 | G          |    1213 | D        | N          |          0 |               |   80024 |    160278
       19 | G          |    1211 | W        | N          |          1 |               |   80016 |    160231
       19 | G          |    1220 | L        | N          |          0 |               |   80020 |    160439
       20 | G          |    1205 | D        | N          |          2 |               |   80004 |    160093
       20 | G          |    1204 | D        | N          |          2 |               |   80007 |    160071
       21 | G          |    1219 | W        | N          |          3 |               |   80017 |    160416
       21 | G          |    1222 | L        | N          |          0 |               |   80010 |    160486
       22 | G          |    1203 | W        | N          |          3 |               |   80009 |    160047
       22 | G          |    1215 | L        | N          |          0 |               |   80015 |    160324
       23 | G          |    1210 | D        | N          |          1 |               |   80030 |    160208
       23 | G          |    1209 | D        | N          |          1 |               |   80032 |    160187
       24 | G          |    1214 | D        | N          |          0 |               |   80008 |    160302
       24 | G          |    1202 | D        | N          |          0 |               |   80019 |    160024
       25 | G          |    1216 | L        | N          |          0 |               |   80035 |    160348
       25 | G          |    1201 | W        | N          |          1 |               |   80034 |    160001
       26 | G          |    1221 | D        | N          |          0 |               |   80001 |    160463
       26 | G          |    1207 | D        | N          |          0 |               |   80002 |    160140
       27 | G          |    1217 | L        | N          |          0 |               |   80011 |    160369
       27 | G          |    1224 | W        | N          |          3 |               |   80022 |    160531
       28 | G          |    1218 | D        | N          |          0 |               |   80003 |    160392
       28 | G          |    1206 | D        | N          |          0 |               |   80023 |    160117
       29 | G          |    1223 | L        | N          |          0 |               |   80031 |    160508
       29 | G          |    1213 | W        | N          |          1 |               |   80025 |    160278
       30 | G          |    1212 | L        | N          |          0 |               |   80026 |    160256
       30 | G          |    1208 | W        | N          |          1 |               |   80028 |    160163
       31 | G          |    1205 | L        | N          |          0 |               |   80033 |    160093
       31 | G          |    1222 | W        | N          |          2 |               |   80027 |    160486
       32 | G          |    1204 | W        | N          |          2 |               |   80021 |    160071
       32 | G          |    1219 | L        | N          |          1 |               |   80024 |    160416
       33 | G          |    1210 | W        | N          |          2 |               |   80018 |    160208
       33 | G          |    1202 | L        | N          |          1 |               |   80012 |    160024
       34 | G          |    1209 | D        | N          |          3 |               |   80014 |    160187
       34 | G          |    1214 | D        | N          |          3 |               |   80006 |    160302
       35 | G          |    1211 | L        | N          |          0 |               |   80036 |    160233
       35 | G          |    1215 | W        | N          |          1 |               |   80029 |    160324
       36 | G          |    1220 | L        | N          |          0 |               |   80005 |    160439
       36 | G          |    1203 | W        | N          |          1 |               |   80013 |    160047
       37 | R          |    1221 | L        | P          |          1 |             4 |   80004 |    160463
       37 | R          |    1213 | W        | P          |          1 |             5 |   80007 |    160278
       38 | R          |    1224 | W        | N          |          1 |               |   80014 |    160531
       38 | R          |    1212 | L        | N          |          0 |               |   80006 |    160256
       39 | R          |    1204 | L        | N          |          0 |               |   80003 |    160071
       39 | R          |    1214 | W        | N          |          1 |               |   80023 |    160302
       40 | R          |    1207 | W        | N          |          2 |               |   80008 |    160140
       40 | R          |    1215 | L        | N          |          1 |               |   80019 |    160324
       41 | R          |    1208 | W        | N          |          3 |               |   80018 |    160163
       41 | R          |    1218 | L        | N          |          0 |               |   80012 |    160392
       42 | R          |    1209 | L        | N          |          0 |               |   80017 |    160187
       42 | R          |    1203 | W        | N          |          4 |               |   80010 |    160047
       43 | R          |    1211 | W        | N          |          2 |               |   80009 |    160231
       43 | R          |    1219 | L        | N          |          0 |               |   80015 |    160416
       44 | R          |    1206 | L        | N          |          1 |               |   80001 |    160117
       44 | R          |    1210 | W        | N          |          2 |               |   80002 |    160208
       45 | Q          |    1213 | L        | P          |          1 |             3 |   80005 |    160278
       45 | Q          |    1214 | W        | P          |          1 |             5 |   80013 |    160302
       46 | Q          |    1224 | W        | N          |          3 |               |   80001 |    160531
       46 | Q          |    1203 | L        | N          |          1 |               |   80002 |    160047
       47 | Q          |    1208 | W        | P          |          1 |             6 |   80016 |    160163
       47 | Q          |    1211 | L        | P          |          1 |             5 |   80020 |    160231
       48 | Q          |    1207 | W        | N          |          5 |               |   80021 |    160140
       48 | Q          |    1210 | L        | N          |          2 |               |   80024 |    160208
       49 | S          |    1214 | W        | N          |          2 |               |   80011 |    160302
       49 | S          |    1224 | L        | N          |          0 |               |   80022 |    160531
       50 | S          |    1207 | W        | N          |          2 |               |   80008 |    160140
       50 | S          |    1208 | L        | N          |          1 |               |   80019 |    160163
       51 | F          |    1214 | W        | N          |          1 |               |   80004 |    160302
       51 | F          |    1207 | L        | N          |          0 |               |   80007 |    160140

Sample Solution:

SQL Code:

-- Selecting ass_ref_name and country_name
SELECT a.ass_ref_name, b.country_name
-- From clause with JOINs between asst_referee_mast, soccer_country, and match_details
FROM asst_referee_mast a
JOIN soccer_country b ON a.country_id = b.country_id
JOIN match_details c ON a.ass_ref_id = c.ass_ref
-- Filtering the results to include only the match with match_no equal to 1
WHERE match_no = 1;

Sample Output:

 ass_ref_name | country_name
--------------+--------------
 Gyorgy Ring  | Hungary
 Vencel Toth  | Hungary
(2 rows)

Code Explanation:

The said query in SQL that retrieves information about the assistant referee and country for the match with match_no equal to 1 from the tables asst_referee_mast, soccer_country, and match_details.
The JOIN keyword is used to join the tables based on columns specified in the ON clause. The asst_referee_mast and soccer_country are joined on the country_id column, while asst_referee_mast and match_details are joined on the ass_ref_id column.
The condition filters only those rows for the match with match_no equal to 1 will be selected.

Alternative Solutions:

Using EXISTS:

-- Selecting ass_ref_name and country_name
SELECT a.ass_ref_name, b.country_name
-- From clause with JOIN between asst_referee_mast and soccer_country using country_id
FROM asst_referee_mast a
JOIN soccer_country b ON a.country_id = b.country_id
-- Using EXISTS to filter results based on a subquery condition
WHERE EXISTS (
    -- Subquery to check if there is at least one match for the assistant referee with match_no equal to 1
    SELECT 1
    -- From clause to select from match_details
    FROM match_details c
    -- Conditions for joining match_details based on ass_ref_id and match_no
    WHERE a.ass_ref_id = c.ass_ref
      AND c.match_no = 1
);

Explanation:

This query uses an EXISTS subquery to filter the results to only include matches with match_no = 1.

Using IN with Subquery:

-- Selecting ass_ref_name and country_name
SELECT a.ass_ref_name, b.country_name
-- From clause with JOIN between asst_referee_mast and soccer_country using country_id
FROM asst_referee_mast a
JOIN soccer_country b ON a.country_id = b.country_id
-- Filtering the results to include only assistant referees with ass_ref_id found in the subquery
WHERE a.ass_ref_id IN (
    -- Subquery to select ass_ref from match_details for the match with match_no equal to 1
    SELECT ass_ref
    -- From clause to select from match_details
    FROM match_details
    -- Condition for filtering match_details based on match_no
    WHERE match_no = 1
);

Explanation:

This query uses a subquery with IN to filter based on match_no.

Relational Algebra Expression:

Relational Algebra Expression: Find the name and country of the referee who assisted the referee in the opening match.

Relational Algebra Tree:

Relational Algebra Tree: Find the name and country of the referee who assisted the referee in the opening match.

Practice Online


Sample Database: soccer

soccer database relationship structure

Query Visualization:

Duration:

Query visualization of Find the name and country of the referee who assisted the referee in the opening match - Duration

Rows:

Query visualization of Find the name and country of the referee who assisted the referee in the opening match - Rows

Cost:

Query visualization of Find the name and country of the referee who assisted the referee in the opening match - Cost

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Previous SQL Exercise: Name and country of referee who managed the final game.
Next SQL Exercise: Referee who assisted in the final match.

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