分組由SHOPNAME計數不同類型的客戶（會員）的

Question

我們有2個表

表1
店，我們有店鋪細節

ShopNo, ShopName 

表2
客戶那裏我們有所有客戶詳細信息

CustomerId, CustomerName, MembershipType, ShopId 

我們試圖查詢什麼是

ShopName SilverMember GoldMember LifeMember 

ABC  45   110  1 

XYZ  90   0   10 

DEF  10   10   7 

有沒有一種方法，以使其能夠

如果Linq中以及和其他良好的只有SQL查詢將提前

問候 莫克沙做的感謝

Answer 1

類似這樣的事情應該訣竅：

select s.ShopName, 
     count(c1.CustomerId) as 'SilverMember', 
     count(c2.CustomerId) as 'GoldMember', 
     count(c3.CustomerId) as 'LifeMember' 
from Shop s 
left outer join Customer c1 on c1.ShopId = s.ShopNo and c1.MembershipType = 'SilverMember' 
left outer join Customer c2 on c2.ShopId = s.ShopNo and c2.MembershipType = 'GoldMember' 
left outer join Customer c3 on c3.ShopId = s.ShopNo and c3.MembershipType = 'LifeMember' 
group by s.ShopName 

Answer 2

如果你想使用LINQ：

var query = from s in context.Shops 
      join c in context.Customers on s.ShopNo equals c.ShopId 
      group c by s.ShopName into g 
      select new 
      { 
       ShopName = g.Key, 
       SilverMember = g.Count(c => c.MembershipType == "SilverMember"), 
       GoldMember= g.Count(c => c.MembershipType == "GoldMember"), 
       LifeMember= g.Count(c => c.MembershipType == "LifeMember"), 
      }; 

Answer 3

假設MembershipType包含實際VARCHAR值SilverMember，GoldMember和LifeMember，應在T-SQL工作：

SELECT 
    [ShopName], COUNT([SilverMember]) AS [SilverMember], COUNT([GoldMember]) AS [GoldMember], COUNT([LifeMember]) AS [LifeMember] 
FROM 
    [Table1] 
    INNER JOIN [Table2] 
     ON [Table1].[ShopNo] = [Table2].[ShopId] 
    PIVOT 
    (
     MAX([MembershipType]) 
      FOR [MembershipType] IN ([SilverMember], [GoldMember], [LifeMember]) 
    ) AS [P] 
GROUP BY 
    [ShopName] 

Example on SQL Fiddle