SQL Server 2022

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create table Player (
ID int,
Email varchar(100),	
FirstName varchar(100));

insert into Player values
(1,'Bob.Lance@gmail.com','Bob'),
(2,'Laura.Davis@gmail.com','Laura'),
(3,'Josh.Stevens@gmail.com','Josh'),
(4,'Alex.Wild@gmail.com','Alex'),
(5,'Bob.Frank@gmail.com','Bob'),
(6,'Alex.Summers@gmail.com','Alex');

create table Sport (
  Sport varchar(100),
  Players varchar(100));

insert into Sport values
('Golf','Laura'),
('Basketball','Josh'),
('Baseball','Alex'),
('Football','Bob'),
('Volleyball','Laura'),
('Swimming','Alex'),
('Driving','Bob'),
('Boxing','Bob');
14 rows affected

SELECT 
  FirstName,
  MIN(Email) AS Email
FROM Player
GROUP BY 
  FirstName
HAVING 
  COUNT(DISTINCT Email) = 1;


FirstName
Email


Josh
Josh.Stevens@gmail.com

Laura
Laura.Davis@gmail.com


UPDATE s
SET s.Players = uniqueMails.Email
FROM Sport s
JOIN 
(SELECT 
  FirstName,
  MIN(Email) AS Email
FROM Player
GROUP BY 
  FirstName
HAVING 
  COUNT(DISTINCT Email) = 1) uniqueMails
ON s.Players = uniqueMails.FirstName;
3 rows affected

SELECT * FROM Sport;


Sport
Players


Golf
Laura.Davis@gmail.com

Basketball
Josh.Stevens@gmail.com

Baseball
Alex

Football
Bob

Volleyball
Laura.Davis@gmail.com

Swimming
Alex

Driving
Bob

Boxing
Bob

Sport	Players
Golf	Laura.Davis@gmail.com
Basketball	Josh.Stevens@gmail.com
Baseball	Alex
Football	Bob
Volleyball	Laura.Davis@gmail.com
Swimming	Alex
Driving	Bob
Boxing	Bob