帮我执行sql查询

Question

我有一张如下表。 我想计算前5％客户的金额和接下来的20％以及接下来的25％和接下来的25％，最后剩下的金额。 这只是DB表的示例。

5%=1, so the sum is 100 
Next 20%=4, so sum=1800(200+500+300+800) 
Next 25%=5, so sum=2900(600+800+500+400+600) 
Next 25%=5, so sum=2500(300+800+300+800+300) 
Rest=1400 

Cus_ID  Amount 
1004    100 
1064    200 
1126    500 
1280    300 
1678    800 
1719    600 
1862    800 
2109    500 
2892    400 
2957    600 
3097    300 
3205    800 
3399    300 
3460    800 
4169    300 
4380    800 
4689    100 
4886    200 
4906    300 

Result 
5% 20% 25% next 25% Rest 
100 1800 2900 2500 1400 

Answer 1

WITH T(Cus_ID,Amount ) AS
(
SELECT 1004, 100 UNION ALL
SELECT 1064, 200 UNION ALL 
SELECT 1126, 500 UNION ALL
SELECT 1280, 300 UNION ALL 
SELECT 1678, 800 UNION ALL 
SELECT 1719, 600 UNION ALL 
SELECT 1862, 800 UNION ALL 
SELECT 2109, 500 UNION ALL 
SELECT 2892, 400 UNION ALL 
SELECT 2957, 600 UNION ALL 
SELECT 3097, 300 UNION ALL 
SELECT 3205, 800 UNION ALL 
SELECT 3399, 300 UNION ALL 
SELECT 3460, 800 UNION ALL 
SELECT 4169, 300 UNION ALL 
SELECT 4380, 800 UNION ALL 
SELECT 4689, 100 UNION ALL 
SELECT 4886, 200 UNION ALL 
SELECT 4906, 300
), T2 AS
(
SELECT *,
       ROW_NUMBER() OVER (ORDER BY Cus_ID) AS RN,
       ROW_NUMBER() OVER (ORDER BY Cus_ID)/ CAST(COUNT(*) OVER() AS FLOAT) AS Pct
FROM T
), T3(Amount, Grp) AS
(
SELECT a.Amount, CASE WHEN ISNULL(b.Pct,0) < 0.05 THEN 1
                      WHEN          b.Pct  < 0.25 THEN 2
                      WHEN          b.Pct  < 0.50 THEN 3
                      WHEN          b.Pct  < 0.75 THEN 4
                      ELSE 5
                  END
FROM T2 a LEFT JOIN T2 b ON b.RN=a.RN-1
)
SELECT SUM(Amount) AS Amount, Grp
FROM T3
GROUP BY  Grp