count中可以使用distinct

CREATE TABLE A
( [购物人] NVARCHAR(10),
  [商品名称] NVARCHAR(10),
  [数量] INT
)

INSERT INTO A
SELECT 'A','甲',2
UNION ALL SELECT 'B','乙',4
UNION ALL SELECT 'C','丙',1
UNION ALL SELECT 'A','丁',2
UNION ALL SELECT 'B','丙',5
UNION ALL SELECT 'C','丙',5

查询出购买了2（包括）种以上商品的购物人

SELECT [购物人] FROM A GROUP BY [购物人] HAVING COUNT(DISTINCT [商品名称])>1