การเขียน SQL คิวรี แปลงแถวไปเป็นคอลัมภ์ ทำอย่างไรครับ

Select 
    Jim.GroupID As JimID,
    Jim.Discount as JimDiscount,
    Thai.GroupID As ThaiID,
    Thai.Discount As ThaiDiscount
From
    xTable As Jim
    Left Join xTable  As Thai On Jim.GroupID + 1 = Thai.GroupID And Jim.GroupID % 2 = 1
Where Thai.GroupID Is Not Null
Order By Jim.GroupID

Select 
    Jim.GroupID As JimID,
    Jim.Discount as JimDiscount,
    Thai.GroupID As ThaiID,
    Thai.Discount As ThaiDiscount,
    ,((((ROW_NUMBER() Over (Order By Jim.GroupID) + 2)/3) - 1) % 3 ) + 1 As Good1500
From
    xTable As Jim
    Left Join xTable As Thai On Jim.GroupID + 1 = Thai.GroupID And Jim.GroupID % 2 = 1
Where Thai.GroupID Is Not Null
Order By Jim.GroupID

Select 
    Jim.GroupID As JimID,
    Jim.Discount as JimDiscount,
    Thai.GroupID As ThaiID,
    Thai.Discount As ThaiDiscount,
    ,((((ROW_NUMBER() Over (Order By Jim.GroupID) + 2)/3) - 1) % 3 ) + 1 As Good1500
From
    xTable As Jim
    Left Join xTable As Thai On Jim.GroupID + 1 = Thai.GroupID And Jim.GroupID % 2 = 1
--Where Thai.GroupID Is Not Null
Order By Jim.GroupID

WITH cte
AS (
	SELECT GroupID AS [ผัว]
		,Discount AS [จ๋า]
		,ROW_NUMBER() OVER (
			ORDER BY GroupID
			) - 1 AS rn
	FROM xTable  AS Ass
	)
	,cte0
AS (
	SELECT *
	FROM cte
	WHERE rn % 3 = 0
	)
	,cte1
AS (
	SELECT *
	FROM cte
	WHERE rn % 3 = 1
	)
	,cte2
AS (
	SELECT *
	FROM cte
	WHERE rn % 3 = 2
	)
SELECT *
FROM cte0
LEFT JOIN cte1 ON cte0.rn + 1 = cte1.rn
LEFT JOIN cte2 ON cte0.rn + 2 = cte2.rn

1. สร้างข้อมูลเพื่อทดสอบ

USE [JimThaiBigDB]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE PROCEDURE [dbo].[Insert_xTable] 
AS
BEGIN
    SET NOCOUNT ON;
    DECLARE @i As int
    SET @i = 0
    WHILE @i < 500000 -- ทดสอบ 5 แสน ระเบียน
      BEGIN
       Insert Into xTable Values(@i, @i + 1)
       SET @i = @i + 1
      END
END

ต้นทุนในการ Select  ค่อนข้างสูงพอสมควร ( 900/1000 วินาที)


[x] มันน่าจะทำได้ดีกว่านี้ เสียดาย และคิดถึงใครบางคน