meilleur sql comptant le nombre d'éléments avec une clause where

Question

J'ai cette requête et je sais qu'il y a une meilleure façon de l'écrire. Voici la requête qui compte les commandes pour savoir ce qu'il reste en stock.

DECLARE @reserveDate as Datetime = '10/5/2011 10:20'

SELECT p.Name 
     , p.Quantity
     , (SELECT COUNT(*) 
          FROM [Order] o 
         WHERE o.ProductId = p.Id 
           AND o.Completed = 1) as Completed 
     , (SELECT COUNT(*) 
          FROM [Order] o 
         WHERE o.ProductId = p.Id 
           AND o.Completed <> 1 
           AND o.ModifiedDate >= @reserveDate) as Reserved 
     , (SELECT COUNT(*) 
          FROM [Order] o 
         WHERE o.ProductId = p.Id 
           AND o.Completed <> 1 
           AND o.ModifiedDate < @reserveDate) as ReserveExpired  
   --, (Quantity - Completed - Reserved) as Available
  FROM Product p 

\====================================

voici un script pour les tables

IF EXISTS ( SELECT  * FROM  sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Order]') AND type IN ( N'U' ) )    DROP TABLE [Order]
IF EXISTS ( SELECT  * FROM  sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Product]') AND type IN ( N'U' ) )  DROP TABLE [Product]

-- Product --
PRINT N' [Product]  ' 
CREATE TABLE Product
    (
      [Id] INT NOT NULL IDENTITY PRIMARY KEY,
      [Name] NVARCHAR(50) ,
      [Quantity] INT ,
    ); 
SET IDENTITY_INSERT Product ON 
INSERT  INTO Product ( [Id] , [Name] ,  [Quantity]) VALUES  ( '1', 'Tea Package',  7000 )
INSERT  INTO Product ( [Id] , [Name] ,  [Quantity]) VALUES  ( '2', 'Sugar Package',  8000)
SET IDENTITY_INSERT Product OFF 

-- Order --
PRINT N' [Order]'

CREATE TABLE [Order]
    (
      [Id] INT NOT NULL IDENTITY PRIMARY KEY ,
      [ProductId] INT   ,
      [Completed] Bit,
      [ModifiedDate] DATETIME 
    ); 
ALTER TABLE [Order] ADD CONSTRAINT FK_Product_Order FOREIGN KEY (ProductId) REFERENCES [Product] (Id) 
GO  
INSERT  INTO [Order] ([ProductId],  [Completed],   [ModifiedDate]  ) VALUES  ( 1, 1,   '10/5/2011 10:10'  )  
INSERT  INTO [Order] ([ProductId],  [Completed],   [ModifiedDate]  ) VALUES  ( 1, 1,   '10/5/2011 10:10'  )  
INSERT  INTO [Order] ([ProductId],  [Completed],   [ModifiedDate]  ) VALUES  ( 1, 0,   '10/5/2011 10:10'  )  
INSERT  INTO [Order] ([ProductId],  [Completed],   [ModifiedDate]  ) VALUES  ( 1, 0,   '10/5/2011 10:10'  )  
INSERT  INTO [Order] ([ProductId],  [Completed],   [ModifiedDate]  ) VALUES  ( 1, 0,   '10/5/2011 11:10'  )  
INSERT  INTO [Order] ([ProductId],  [Completed],   [ModifiedDate]  ) VALUES  ( 1, 0,   '10/6/2011 11:10'  )  
INSERT  INTO [Order] ([ProductId],  [Completed],   [ModifiedDate]  ) VALUES  ( 1, 0,   '10/6/2011 11:10'  )  
INSERT  INTO [Order] ([ProductId],  [Completed],   [ModifiedDate]  ) VALUES  ( 2, 1,   '10/5/2011 10:10'  )  
INSERT  INTO [Order] ([ProductId],  [Completed],   [ModifiedDate]  ) VALUES  ( 2, 1,   '10/5/2011 10:10'  )  
INSERT  INTO [Order] ([ProductId],  [Completed],   [ModifiedDate]  ) VALUES  ( 2, 0,   '10/5/2011 10:10'  )  
INSERT  INTO [Order] ([ProductId],  [Completed],   [ModifiedDate]  ) VALUES  ( 2, 0,   '10/6/2011 10:10'  )

Answer 1

Vous pouvez remplacer les sous-requêtes en utilisant :

   SELECT p.Name 
        , p.Quantity
        , SUM(CASE WHEN o.completed = 1 THEN 1 ELSE 0 END) AS Completed 
        , SUM(CASE WHEN o.completed <> 1 AND o.ModifiedDate >= @reserveDate THEN 1 ELSE 0 END) AS Reserved 
        , SUM(CASE WHEN o.completed <> 1 AND o.ModifiedDate < @reserveDate THEN 1 ELSE 0 END) AS ReserveExpired  
        , p.Quantity - 
          SUM(CASE WHEN o.completed = 1 THEN 1 ELSE 0 END) -
          SUM(CASE WHEN o.completed <> 1 AND o.ModifiedDate >= @reserveDate THEN 1 ELSE 0 END) AS available
     FROM Product p 
LEFT JOIN ORDER o ON o.productid = p.id
 GROUP BY p.Name, p.Quantity

Alternativement, le texte suivant est équivalent et plus facile à lire :

SELECT x.name, 
       x.quantity,
       x.completed,
       x.reserved,
       x.reserveexpired,
       x.quantity - x.completed - x.reserved AS available
  FROM (SELECT p.Name 
             , p.Quantity
             , SUM(CASE WHEN o.completed = 1 THEN 1 ELSE 0 END) AS Completed 
             , SUM(CASE WHEN o.completed <> 1 AND o.ModifiedDate >= @reserveDate THEN 1 ELSE 0 END) AS Reserved 
             , SUM(CASE WHEN o.completed <> 1 AND o.ModifiedDate < @reserveDate THEN 1 ELSE 0 END) AS ReserveExpired  
          FROM Product p 
     LEFT JOIN ORDER o ON o.productid = p.id
      GROUP BY p.Name, p.Quantity) x

Answer 2

Vous pouvez soustraire des éléments dans T-SQL même, quelque chose comme :

SELECT A - B AS C FROM TABLE WHERE ID=1

Bien que je ne sois pas sûr de la meilleure façon de le faire avec vos sous-requêtes. Je ne sais pas non plus si vous avez besoin de conserver la quantité réelle, les valeurs Completed, Reserved et RerservedExpired dans votre programmation ou si vous en avez seulement besoin pour calculer la quantité disponible. Si vous en avez besoin en dehors de SQL, la soustraction à l'intérieur ne vous sera d'aucune utilité.

Answer 3

Vous pourriez utiliser CROSS APPLY / OUTER APPLY opérateurs :

CREATE INDEX aaa
ON [Order](ProductId)
INCLUDE (Completed,ModifiedDate);

PRINT '***** Sol1 *****'
SELECT 
     p.Name 
    ,p.Quantity
    ,ISNULL(ca.Completed,0) Completed
    ,ISNULL(ca.Reserved,0) Reserved
    ,ISNULL(ca.ReserveExpired,0) ReserveExpired
    ,p.Quantity - ISNULL(ca.Completed,0) - ISNULL(ca.Reserved,0) Available
FROM Product p 
OUTER APPLY
(
    SELECT 
         SUM(CASE WHEN o.Completed = 1 THEN 1 ELSE 0 END) Completed
        ,SUM(CASE WHEN o.Completed <> 1 AND o.ModifiedDate >= @reserveDate THEN 1 ELSE 0 END) Reserved
        ,SUM(CASE WHEN o.Completed <> 1 AND o.ModifiedDate < @reserveDate THEN 1 ELSE 0 END) ReserveExpired
    FROM [Order] o --WITH(FORCESEEK) or WITH(INDEX=aaa)
    WHERE o.ProductId = p.Id 
) ca;

PRINT '***** Sol2 *****'
SELECT 
     p.Name 
    ,p.Quantity
    ,ISNULL(q.Completed,0) Completed
    ,ISNULL(q.Reserved,0) Reserved
    ,ISNULL(q.ReserveExpired,0) ReserveExpired
    ,p.Quantity - ISNULL(q.Completed,0) - ISNULL(q.Reserved,0) Available
FROM    Product p
LEFT MERGE JOIN --or LEFT JOIN
(
    SELECT   o.ProductId
            ,SUM(CASE WHEN o.Completed = 1 THEN 1 ELSE 0 END) Completed
            ,SUM(CASE WHEN o.Completed <> 1 AND o.ModifiedDate >= @reserveDate THEN 1 ELSE 0 END) Reserved
            ,SUM(CASE WHEN o.Completed <> 1 AND o.ModifiedDate < @reserveDate THEN 1 ELSE 0 END) ReserveExpired     
    FROM    [Order] o 
    GROUP BY o.ProductId
) q ON p.Id = q.ProductId;