¿Cómo combino datos de varias filas en una sola?

Usando PIVOT puede hacer lo siguiente

With SampleData AS 
(
SELECT 'Team1' as Team , '[email protected]' as email, 'A' as Groups
UNION SELECT 'Team1' as Team , '[email protected]' as email, 'B' as Groups
UNION SELECT 'Team1' as Team , '[email protected]' as email, 'C' as Groups
UNION SELECT 'Team2' as Team , '[email protected]' as email, 'A' as Groups
UNION SELECT 'Team2' as Team , '[email protected]' as email, 'B' as Groups
UNION SELECT 'Team2' as Team , '[email protected]' as email, 'C' as Groups
)
SELECT Team, A, B,C FROM 
(SELECT * FROM SampleData) source
PIVOT
(MAX(email) FOR Groups IN ([A], [B], [C]) )as pvt

Produce

Team  A                B                C
----- ---------------- ---------------- ----------------
Team1 [email protected] [email protected] [email protected]
Team2 [email protected] [email protected] [email protected]

Vea un ejemplo de Data.SE en funcionamiento

En una base de datos que no es compatible con PIVOT, puede realizar múltiples combinaciones en su tabla. Aunque es posible que desee hacerlo de todos modos, ya que, como señaló GBN, ya que no estamos utilizando un agregado.

With SampleData AS 
(
SELECT 'Team1' as Team , '[email protected]' as email, 'A' as Groups
UNION SELECT 'Team1' as Team , '[email protected]' as email, 'B' as Groups
UNION SELECT 'Team1' as Team , '[email protected]' as email, 'C' as Groups
UNION SELECT 'Team2' as Team , '[email protected]' as email, 'A' as Groups
UNION SELECT 'Team2' as Team , '[email protected]' as email, 'B' as Groups
UNION SELECT 'Team2' as Team , '[email protected]' as email, 'C' as Groups
)

SELECT 
    source.Team,
    A.email,
    B.email,
    C.email
FROM 
    (SELECT DISTINCT TEAM From SampleData) source
    LEFT JOIN SampleData A 
    ON source.Team = A.Team
     AND A.GROUPS = 'A'
    LEFT JOIN SampleData B 
    ON source.Team = B.Team
    AND B.GROUPS = 'B'
    LEFT JOIN SampleData C 
    ON source.Team = C.Team
    AND C.GROUPS = 'C'

Vea un ejemplo de Data.SE