[MSSQL]FOR XML AUTO II

这次的测试数据稍有复杂,先看下SQL脚本:

CREATE TABLE Person(
    ID INT IDENTITY(1,1) NOT NULL,
    Name NVARCHAR(20) NOT NULL DEFAULT(''),
    Age INT DEFAULT(0) NOT NULL,
    Sex BIT DEFAULT(0) NOT NULL
)
--DROP TABLE [Order]
CREATE TABLE [Order](
    ID INT IDENTITY(1,1) PRIMARY KEY,
    PersonID INT DEFAULT(0) NOT NULL,
    TotalPrice DECIMAL DEFAULT(0) NOT NULL
)

CREATE TABLE Product(
    ID INT IDENTITY(1,1) PRIMARY KEY,
    Price DECIMAL(8,2) DEFAULT(0.00) NOT NULL,
    Img NVARCHAR(50) DEFAULT('') NOT NULL
)

CREATE TABLE OrderDetail(
    ID INT IDENTITY(1,1) PRIMARY KEY,
    OrderID INT DEFAULT(0) NOT NULL,
    ProductID INT DEFAULT(0) NOT NULL,
    Price DECIMAL(8,2) DEFAULT(0.00) NOT NULL
)


INSERT INTO Person(Name,Age,Sex)
SELECT '张三',28,1 UNION ALL
SELECT '李四',28,1 UNION ALL
SELECT '王五',28,1

INSERT INTO [Order](PersonID,TotalPrice)
SELECT 1,100.0 UNION ALL
SELECT 1,111.0 UNION ALL
SELECT 2,112.0 UNION ALL
SELECT 3,98.0 UNION ALL
SELECT 3,150.49 UNION ALL
SELECT 3,58

INSERT INTO Product(Price,Img)
SELECT 101.0,'1.png' UNION ALL
SELECT 102.0,'2.png' UNION ALL
SELECT 103.0,'3.png' UNION ALL
SELECT 104.0,'4.png' UNION ALL
SELECT 105.0,'5.png'

INSERT INTO OrderDetail(OrderID,ProductID,Price)
SELECT TOP 3 3,ID,Price FROM Product


SELECT * FROM Person
SELECT * FROM [Order]
SELECT * FROM Product
SELECT * FROM OrderDetail

Person
ID          Name                 Age         Sex
----------- -------------------- ----------- -----
1           张三                   28          1
2           李四                   28          1
3           王五                   28          1
(3 行受影响)


[Order]
ID          PersonID    TotalPrice
----------- ----------- ---------------------------------------
1           1           100
2           1           111
3           2           112
4           3           98
5           3           150
6           3           58
(6 行受影响)


Product
ID          Price                                   Img
----------- --------------------------------------- --------------------------------------------------
1           101.00                                  1.png
2           102.00                                  2.png
3           103.00                                  3.png
4           104.00                                  4.png
5           105.00                                  5.png
(5 行受影响)


OrderDetail
ID          OrderID     ProductID   Price
----------- ----------- ----------- ---------------------------------------
1           1           1           101.00
2           1           2           102.00
3           1           3           103.00
4           1           4           104.00
5           1           5           105.00
6           2           1           101.00
7           2           2           102.00
8           2           3           103.00
9           3           1           101.00
10          3           2           102.00
11          3           3           103.00
(11 行受影响)

理下其中的关系:

会员表Person与订单表Order为一对多关系,其中Order.PersonID = Person.ID

订单表与订单详情表为一对多关系,其中OrderDetail.OrderID = Order.ID

产品表与订单详情表为一对多关系,其中OrderDetail.ProductID = Product.ID

如下图1

图1

可以开始了:

先来看有那些订单,分别为谁的订单,以及订单详情,SQL脚本及查询结果如下

SELECT
[Order].ID,
[Order].PersonID,
OrderDetail.OrderID,
OrderDetail.ProductID,
OrderDetail.Price
FROM [Order]
    INNER JOIN OrderDetail ON [Order].ID = OrderDetail.OrderID
FOR XML AUTO,ROOT('Record')

查询结果如下

<Record>
  <Order ID="1" PersonID="1">
    <OrderDetail OrderID="1" ProductID="1" Price="101.00" />
    <OrderDetail OrderID="1" ProductID="2" Price="102.00" />
    <OrderDetail OrderID="1" ProductID="3" Price="103.00" />
    <OrderDetail OrderID="1" ProductID="4" Price="104.00" />
    <OrderDetail OrderID="1" ProductID="5" Price="105.00" />
  </Order>
  <Order ID="2" PersonID="1">
    <OrderDetail OrderID="2" ProductID="1" Price="101.00" />
    <OrderDetail OrderID="2" ProductID="2" Price="102.00" />
    <OrderDetail OrderID="2" ProductID="3" Price="103.00" />
  </Order>
  <Order ID="3" PersonID="2">
    <OrderDetail OrderID="3" ProductID="1" Price="101.00" />
    <OrderDetail OrderID="3" ProductID="2" Price="102.00" />
    <OrderDetail OrderID="3" ProductID="3" Price="103.00" />
  </Order>
</Record>

调整下查询列的顺序,再看下结果,变了啊:

SELECT
OrderDetail.OrderID,
OrderDetail.ProductID,
OrderDetail.Price,
[Order].ID,
[Order].PersonID
FROM [Order]
    INNER JOIN OrderDetail ON [Order].ID = OrderDetail.OrderID
FOR XML AUTO,ROOT('Record')

输出结果很猛:

<Record>
  <OrderDetail OrderID="1" ProductID="1" Price="101.00">
    <Order ID="1" PersonID="1" />
  </OrderDetail>
  <OrderDetail OrderID="1" ProductID="2" Price="102.00">
    <Order ID="1" PersonID="1" />
  </OrderDetail>
  <OrderDetail OrderID="1" ProductID="3" Price="103.00">
    <Order ID="1" PersonID="1" />
  </OrderDetail>
  <OrderDetail OrderID="1" ProductID="4" Price="104.00">
    <Order ID="1" PersonID="1" />
  </OrderDetail>
  <OrderDetail OrderID="1" ProductID="5" Price="105.00">
    <Order ID="1" PersonID="1" />
  </OrderDetail>
  <OrderDetail OrderID="2" ProductID="1" Price="101.00">
    <Order ID="2" PersonID="1" />
  </OrderDetail>
  <OrderDetail OrderID="2" ProductID="2" Price="102.00">
    <Order ID="2" PersonID="1" />
  </OrderDetail>
  <OrderDetail OrderID="2" ProductID="3" Price="103.00">
    <Order ID="2" PersonID="1" />
  </OrderDetail>
  <OrderDetail OrderID="3" ProductID="1" Price="101.00">
    <Order ID="3" PersonID="2" />
  </OrderDetail>
  <OrderDetail OrderID="3" ProductID="2" Price="102.00">
    <Order ID="3" PersonID="2" />
  </OrderDetail>
  <OrderDetail OrderID="3" ProductID="3" Price="103.00">
    <Order ID="3" PersonID="2" />
  </OrderDetail>
</Record>

XML结构变了,是变了,MSDN中是这样解释滴:

第一个ID引用自Order表,故创建Order节点
PersonID同样引用自Order表,第一步已经创建Order节点,故此处仅为节点添加PersonID属性
接下来三列OrderID,ProductID,Price引用OrderDetail表,因此在Order节点下创建OrderDetail子节点
列的别名显示为属性名称,没有别名使用列名
节点的名称使用表别名,没有别名使用表名

Order By对XML结构的影响

再看个例子,对Order.PersonID排序:

SELECT
    [Order].ID,
    [Order].PersonID,
    OrderDetail.OrderID,
    OrderDetail.ProductID,
    OrderDetail.Price
FROM [Order]
    INNER JOIN OrderDetail ON [Order].ID = OrderDetail.OrderID
ORDER BY [Order].PersonId
FOR XML AUTO,ROOT('Record')

输出结果:

<Record>
  <Order ID="1" PersonID="1">
    <OrderDetail OrderID="1" ProductID="1" Price="101.00" />
    <OrderDetail OrderID="1" ProductID="2" Price="102.00" />
    <OrderDetail OrderID="1" ProductID="3" Price="103.00" />
    <OrderDetail OrderID="1" ProductID="4" Price="104.00" />
    <OrderDetail OrderID="1" ProductID="5" Price="105.00" />
  </Order>
  <Order ID="2" PersonID="1">
    <OrderDetail OrderID="2" ProductID="1" Price="101.00" />
    <OrderDetail OrderID="2" ProductID="2" Price="102.00" />
    <OrderDetail OrderID="2" ProductID="3" Price="103.00" />
  </Order>
  <Order ID="3" PersonID="2">
    <OrderDetail OrderID="3" ProductID="1" Price="101.00" />
    <OrderDetail OrderID="3" ProductID="2" Price="102.00" />
    <OrderDetail OrderID="3" ProductID="3" Price="103.00" />
  </Order>
</Record>

其实这个结果与第一个查询结果是一样滴,行默认顺序会影响XML结果,排序也会影响XML结构,只要当前行与上一行数据可以合并时,就会影响XML结构

再来看一个排序影响XML结构的例子,这次以OrderDetail.ProductID排序,直接看结果:

<Record>
  <Order ID="1" PersonID="1">
    <OrderDetail OrderID="1" ProductID="1" Price="101.00" />
  </Order>
  <Order ID="2" PersonID="1">
    <OrderDetail OrderID="2" ProductID="1" Price="101.00" />
  </Order>
  <Order ID="3" PersonID="2">
    <OrderDetail OrderID="3" ProductID="1" Price="101.00" />
    <OrderDetail OrderID="3" ProductID="2" Price="102.00" />
  </Order>
  <Order ID="2" PersonID="1">
    <OrderDetail OrderID="2" ProductID="2" Price="102.00" />
  </Order>
  <Order ID="1" PersonID="1">
    <OrderDetail OrderID="1" ProductID="2" Price="102.00" />
    <OrderDetail OrderID="1" ProductID="3" Price="103.00" />
  </Order>
  <Order ID="2" PersonID="1">
    <OrderDetail OrderID="2" ProductID="3" Price="103.00" />
  </Order>
  <Order ID="3" PersonID="2">
    <OrderDetail OrderID="3" ProductID="3" Price="103.00" />
  </Order>
  <Order ID="1" PersonID="1">
    <OrderDetail OrderID="1" ProductID="4" Price="104.00" />
    <OrderDetail OrderID="1" ProductID="5" Price="105.00" />
  </Order>
</Record>

FOR XML AUTO大致如此,如果对XML结果不太关注,并且查询语句不会经常变化,那么推荐使用FOR XML AUTO

但,要想更加灵活一点,精确控制XML的结构及属性和ELEMENT,那么需要使用FOR XML EXPLICIT模式,这个模式下篇介绍

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