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Question

我是數據庫的新手。我用兩張桌子遇到了一個奇怪的問題。請讓我知道解決方案。請測量值低於

一個ProductCentre表 prdcntrId（主鍵），prdcntrname場景

一個ApplicationType表 apptypeid（主鍵） prdcntreid（外鍵ProductCentre） apptypname

ProductCentre table  ||   ApplicationType table 
          || 
prdcntrId prdcntrname ||  apptypeid prdcntreid apptypname 
001   Delhi  ||   11   001   Busines 
002   Mumbai  ||   12   003   Engg 
003   Hyd   ||   13   001   Soft 
             14   002   Science 

最終結果應該是這樣的 產品中心可以有任何類型的應用程序，如德里可以有許多業務，軟應用程序與孟買相同，hyd

 
--------------------------------------------------------------------- 
prdcntrname    Busines  Engg Soft  Science 
--------------------------------------------------------------------- 
Delhi      1    0  1   0 
--------------------------------------------------------------------- 
Mumbai      0    1  0   1 
--------------------------------------------------------------------- 
Hyd      0    1  0   0 
--------------------------------------------------------------------- 

這個解決方案可能來自這兩個表。請幫我在這種情況下

感謝， KK

Answer 1

您可以嘗試使用PIVOT

喜歡的東西（SQL Server）的

DECLARE @ProductCentre table(
     prdcntrId INT, 
     prdcntrname VARCHAR(50) 
) 

DECLARE @ApplicationType table(
     apptypeid INT, 
     prdcntreid INT, 
     apptypname VARCHAR(50) 
) 

INSERT INTO @ProductCentre SELECT 001,'Delhi' 
INSERT INTO @ProductCentre SELECT 002,'Mumbai' 
INSERT INTO @ProductCentre SELECT 003,'Hyd' 

INSERT INTO @ApplicationType SELECT 11,001,'Busines' 
INSERT INTO @ApplicationType SELECT 12,003,'Engg' 
INSERT INTO @ApplicationType SELECT 13,001,'Soft' 
INSERT INTO @ApplicationType SELECT 14,002,'Science' 

SELECT p.* 
FROM @ProductCentre p INNER JOIN 
     @ApplicationType a ON p.prdcntrId = a.prdcntreid 
PIVOT 
     (COUNT(apptypname) FOR apptypname IN ([Busines], 
                [Engg], 
                [Soft], 
                [Science])) p 

Answer 2

如果`apptypname」類型固定的，那麼這可以工作：

select 
c.prdcntrname, 
Busines = (select count(*) 
      from ApplicationType at 
      where at.prdcntreid = c.prdcntreid and apptypname = 'Business'), 
Engg = (select count(*) 
      from ApplicationType at 
      where at.prdcntreid = c.prdcntreid and apptypname = 'Engg'), 
Soft = (select count(*) 
      from ApplicationType at 
      where at.prdcntreid = c.prdcntreid and apptypname = 'Soft'), 
Science = (select count(*) 
      from ApplicationType at 
      where at.prdcntreid = c.prdcntreid and apptypname = 'Science'), 

from ProductCentre c 
order by c.prdcntrname