SQL/LINQ的的GroupBy與最小值，並根據列

Question

我與這些例子行的表：

 
CouponID ShopID ShopLongitude ShopLatitude 
365  1881 55,5574105 9,9613295 
365  23550 55,5510846 9,9936818 
365  33550 55,6220936 10,0663895 
365  33551 55,5573436 9,9611765 
366  1881 55,5574105 9,9613295 
366  23550 55,5510846 9,9936818 
367  1881 55,5574105 9,9613295 
533  1881 55,5574105 9,9613295 
533  23550 55,5510846 9,9936818 
533  33550 55,6220936 10,0663895 
533  33551 55,5573436 9,9611765 
354  1881 55,5574105 9,9613295 
354  23550 55.5510846 9,9936818 
354  33550 55,6220936 10,0663895 
354  33551 55,5573436 9,9611765 

我想有結果，每最近ShopID CouponID

我已經有查詢：

SELECT CouponID, MIN (dbo.DistanceBetween (53.54613,9.98537,ShopLatitude,ShopLongitude)) as distance 
FROM Table 
GROUP BY CouponID 
ORDER BY CouponID, distance ASC 

輸出該CouponID並向ShopID的最小距離爲每個優惠券：

 
CouponID distance 
354  0,778524633472375 
365  0,778524633472375 
366  0,778524633472375 
367  2,02548179145764 

在LINQ的語句如下：

var coupon = (from c in dbContext.table 
         group c by c.CouponID into cgrp 
         select new 
         { 
         CouponID = cgrp.Key, 
         Distance = cgrp.Min(c => DistanceBetween(latitude, longitude, c.ShopLatitude, c.ShopLongitude)) 
         }) 
         .OrderBy(c => c.CouponID).ThenBy(c => DistanceBetween(latitude, longitude, c.ShopLatitude, c.ShopLongitude)); 

我怎麼也拿回相關ShopID從 查詢和LINQ聲明的最小距離？

Answer 1

SELECT c.CouponID, c.ShopID, nearest.distance 
FROM 
Coupons C JOIN 
(
    SELECT CouponID, MIN (dbo.DistanceBetween (53.54613,9.98537,ShopLat,ShopLon)) as distance 
    FROM Coupons 
    GROUP BY CouponID 
) nearest on c.CouponID = nearest.CouponID 
      AND dbo.DistanceBetween (53.54613,9.98537,ShopLat,ShopLon) = nearest.distance 
ORDER BY CouponID, distance ASC 

Answer 2

只是修改您的SQL查詢來執行分組並加入你想要的。

創建一個表來保存距離，然後選擇couponid和shopid匹配的min。