SQL Query，Union Order by like tree

Question

您好我有一个像

这样的查询

SELECT 4 AS sortf,XX FROM Table GROUP BY Y
UNION 
SELECT 1 AS sortf,XX FROM Table GROUP BY Y
UNION 
SELECT 2 AS sortf,XX FROM Table GROUP BY Y
UNION
SELECT 3 AS sortf,XX FROM Table GROUP BY Y
ORDER BY 3,2

我的问题是第2行和第3行没有按树排序。我尝试了一些其他组合，但它没有用。

Answer 1

如果要根据数字对数据集进行排序，将代码和联合放入公用表表达式，并使用ROW_NUMBER（）函数生成行号，如下所示：

WITH CTE
AS
(
    SELECT 4 AS sortf, productid FROM Production.Products 
    UNION 
    SELECT 1 AS sortf,productid FROM Production.Products
    UNION 
    SELECT 2 AS sortf,productid FROM Production.Products
    UNION
    SELECT 3 AS sortf,productid FROM Production.Products
)
SELECT *, ROW_NUMBER() OVER (ORDER BY productid)  AS SortOrder
FROM CTE
ORDER BY SortOrder