probe con esto y si me sale, tienes mas campos en tu query?
Código SQL:
Ver originalDROP TABLE #t1
CREATE TABLE #t1 (campo1 VARCHAR(10), campo2 datetime)
INSERT INTO #t1 VALUES ('1',getdate())
INSERT INTO #t1 VALUES ('1',getdate())
INSERT INTO #t1 VALUES ('1',getdate())
INSERT INTO #t1 VALUES ('2',getdate())
INSERT INTO #t1 VALUES ('1',getdate())
INSERT INTO #t1 VALUES ('2',getdate())
INSERT INTO #t1 VALUES ('1',getdate())
INSERT INTO #t1 VALUES ('1',getdate())
INSERT INTO #t1 VALUES ('1',getdate())
INSERT INTO #t1 VALUES ('3',getdate())
INSERT INTO #t1 VALUES ('3',getdate())
INSERT INTO #t1 VALUES ('1',getdate())
INSERT INTO #t1 VALUES ('2',getdate())
GO
SELECT ROW_NUMBER() OVER (partition BY campo1 ORDER BY campo1) AS id, campo1,campo2 FROM #t1
1 1 2012-09-06 12:27:09.197
2 1 2012-09-06 12:27:09.197
3 1 2012-09-06 12:27:09.200
4 1 2012-09-06 12:27:09.200
5 1 2012-09-06 12:27:09.200
6 1 2012-09-06 12:27:09.203
7 1 2012-09-06 12:27:09.200
8 1 2012-09-06 12:27:09.203
1 2 2012-09-06 12:27:09.203
2 2 2012-09-06 12:27:09.200
3 2 2012-09-06 12:27:09.200
1 3 2012-09-06 12:27:09.203
2 3 2012-09-06 12:27:09.203
podrias poner el codigo que estas usando y los datos tal cual te los regresa tu proceso??
saludos!