Константин Цветков

SELECT ID, User, (SELECT COUNT(*) FROM a AS b WHERE b.User = a.User) AS Matches FROM a

SELECT a.ID, 
DATEADD( s, RAND( CONVERT( INT, CAST( NEWID() AS BINARY(16) ), 1)) * 252460800, '20080101' ) AS dt
FROM 
(VALUES (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (15)) AS A (ID)
CROSS JOIN
(VALUES  (1),  (2),  (3),  (4),  (5),  (6),  (7),  (8),  (9), (10), 
        (11), (12), (13), (14), (15), (16), (17), (18), (19), (20),
        (21), (22), (23), (24), (25), (26), (27), (28), (29), (30)) AS B(C)
ORDER BY NEWID()

SELECT t.id, t.country, t.salary 
  FROM t
    INNER JOIN 
      ( SELECT country, max(salary) AS max_salary FROM t GROUP BY country ) tm
        ON t.country = tm.country AND t.salary = tm.max_salary