Question

我想从三个表中获取信息，如：

项目

itemId  Name   Quantity Price  
1       Pen    100      1,0
2       Pencil 100      0,5
3       Glue   20       1,5

ItemFiles

itemId fileId
1      1001
1      1002
1      1003
2      2001
3      3001
3      3002

phisicsFile

fileId Filename 
1001   order_101_20170621.pdf
1002   delivery_404_20170627.pdf
1003   payement_20170630.pdf
2001   order_102_20170623.pdf
3001   order_103_20170624.pdf
3002   delivery_404_20170627.pdf

我需要一个像这样的结果的单一查询

Name    Quantity    Price     Order Delivery   Payed
Pen         100       1,0      True   True    True

或

Pencil      100       0,5      True   False   False

或

Glue         20       1,5      True   True    False

我尝试这样的事情

SELECT
     I.itemId                           AS Id,
    CASE 
            WHEN FS.Filename like '%'Order'%' THEN 'True' 
            ELSE 'False' 
    END                                                        AS Order


FROM       Item  I

 left join 
ItemFiles on I.itemId = IF.itemId
left join phisicsFile PF on (IF.file_id = PF.fileId AND PF.Filename like '%order%')

WHERE  I.itemId= @itemId

但是我在结果中得到重复的行

Answer 1

您不需要LEFT JOIN，只需加入GROUP BY即可。然后使用条件计数来检查每种文件类型的存在。

<强> SQL DEMO

SELECT I.[itemId], I.[Name], I.[Quantity], I.[Price],
       CAST( COUNT(CASE WHEN P.Filename like '%order%' THEN 1 END) as bit) as [Orders],
       CAST( COUNT(CASE WHEN P.Filename like '%delivery%' THEN 1 END) as bit) as [Delivery],
       CAST( COUNT(CASE WHEN P.Filename like '%payement%' THEN 1 END) as bit) as [Payment]
FROM Items I
JOIN ItemFiles  F
  ON I.[itemId] = F.[itemId]
JOIN phisicsFile P
  ON F.[fileId] = P.[fileId]
GROUP BY   I.[itemId], I.[Name], I.[Quantity], I.[Price]

<强>输出

Answer 2

这是另一种选择......

IF OBJECT_ID('tempdb..#Item', 'U') IS NOT NULL 
DROP TABLE #Item;

CREATE TABLE #Item (
    ItemId INT NOT NULL PRIMARY KEY CLUSTERED,
    Name VARCHAR(20) NOT NULL,
    Quantity INT NOT NULL,
    Price MONEY NOT NULL 
    );
INSERT #Item (ItemId, Name, Quantity, Price) VALUES 
(1, 'Pen', 100, 1.0),
(2, 'Pencil', 100, 0.5),
(3, 'Glue', 20, 1.5);

IF OBJECT_ID('tempdb..#ItemFiles', 'U') IS NOT NULL 
DROP TABLE #ItemFiles;

CREATE TABLE #ItemFiles (
    ItemId INT NOT NULL,
    FileId INT NOT NULL,
    PRIMARY KEY CLUSTERED (ItemId, FileId)
    );
INSERT #ItemFiles (ItemId, FileId) VALUES
(1, 1001),
(1, 1002),
(1, 1003),
(2, 2001),
(3, 3001),
(3, 3002);

IF OBJECT_ID('tempdb..#PhisicsFile', 'U') IS NOT NULL 
DROP TABLE #PhisicsFile;

CREATE TABLE #PhisicsFile (
    FieldId INT NOT NULL PRIMARY KEY CLUSTERED,
    FileName VARCHAR(50) NOT NULL 
    );
INSERT #PhisicsFile (FieldId, FileName) VALUES
(1001, 'order_101_20170621.pdf'),
(1002, 'delivery_404_20170627.pdf'),
(1003, 'payement_20170630.pdf'),
(2001, 'order_102_20170623.pdf'),
(3001, 'order_103_20170624.pdf'),
(3002, 'delivery_404_20170627.pdf');

--=================================================

SELECT 
    i.ItemId,
    i.Name,
    i.Quantity,
    i.Price,
    [Order] = CASE WHEN xif.HasOrder = 1 THEN 'True' ELSE 'False' END,
    Delivery = CASE WHEN xif.HasDelivery = 1 THEN 'True' ELSE 'False' END,
    Payement = CASE WHEN xif.HasPayement = 1 THEN 'True' ELSE 'False'END
FROM 
    #Item i
    OUTER APPLY (
        SELECT 
            HasOrder = MAX(CASE WHEN pf.FileName LIKE 'order%' THEN 1 END),
            HasDelivery = MAX(CASE WHEN pf.FileName LIKE 'delivery%' THEN 1 END),
            HasPayement = MAX(CASE WHEN pf.FileName LIKE 'payement%' THEN 1 END)
        FROM 
            #ItemFiles ifi
            JOIN #PhisicsFile pf
                ON ifi.FileId = pf.FieldId
        WHERE 
            i.ItemId = ifi.ItemId
        ) xif;

HTH，杰森

Answer 3

select Id,Name,Quantity,Price,
    case when [order] = 1 then 'true' else 'false' end as [order],
    case when [delivery]=1 then 'true' else 'false' end as [delivery],
    case when [payement]=1 then 'true' else 'false' end as [payement]
from 
(SELECT
     I.itemId AS Id,
     I.Name,
     I.Quantity,
     I.Price,
     SUBSTRING(PF.Filename,0,charindex('_',PF.Filename))  stat                               
FROM       #Item  I
INNER join #ItemFiles Itf on I.itemId = Itf.itemId
INNER join #phisicsFile PF on Itf.fileId = PF.fileId) as s
PIVOT
(
count(stat) for stat IN ([order],[delivery],[payement])
) as p

如果您使用的是sql 2016，则可以使用STRING_SPLIT（字符串，分隔符）代替子字符串。

Answer 4

onCreate()

SQL LEFT JOIN在三个表上有条件

4 个答案: