ROW_NUMBER、RANK()、DENSE_RANK()和OVER的使用

/*以FoodPrice列排序并显示排序后的行号*/
SELECT ROW_NUMBER() OVER(ORDER BY FoodPrice DESC) AS RowId,* FROM dbo.Food

ROW_NUMBER()

/*以FoodType分组，然后以FoodPrice排序并显示所在分组的相应行号*/
SELECT ROW_NUMBER() OVER(PARTITION BY FoodType ORDER BY FoodPrice DESC) AS RowId,* FROM dbo.Food

RANK()

/*以FoodType分组，然后以FoodPrice排序并显示所在分组的相应行号，如果排序字段字相等则显示相同的行号，
并跳过所在的真实行号*/
SELECT RANK() OVER(PARTITION BY FoodType ORDER BY FoodPrice) AS RowID,* FROM dbo.Food

DENSE_RANK()

/*以FoodType分组，然后以FoodPrice排序并显示所在分组的相应行号，如果排序字段字相等则显示相同的行号，
忽略相同行号，依次递增*/
SELECT DENSE_RANK() OVER(PARTITION BY FoodType ORDER BY FoodPrice) AS RowID,* FROM dbo.Food