您的位置：首页 > 数据库

SQL中FOR XML子句的各种用法

2009-04-29 12:02 351 查看

FORXML子句有四种最基本的模式，如上图所示：

1、AUTO模式：返回数据表为起表名的元素，每一列的值返回为属性；

2、RAW模式：返回数据行为<Row>元素，每一列的值作为<Row>元素的属性；

3、PATH模式：通过简单的XPath语法来允许用户自定义嵌套的XML结构、元素、属性值

4、EXPLICIT模式：通过SELECT语法定义输出XML的结构

具体实例如下：

1、AUTO模式

(1).SQL语句：

SELECTEmployeeID,FirstName,LastNameFROMEmployeesFORXMLAUTO,XMLSCHEMA

(2).所生成的XML文件：

返回XML文件的XMLSchema

<xsd:schematargetNamespace="urn:schemas-microsoft-com:sql:SqlRowSet1"xmlns:schema="urn:schemas-microsoft-com:sql:SqlRowSet1"xmlns:xsd="http://www.w3.org/2001/XMLSchema"xmlns:sqltypes="http://schemas.microsoft.com/sqlserver/2004/sqltypes"elementFormDefault="qualified">

<xsd:importnamespace="http://schemas.microsoft.com/sqlserver/2004/sqltypes"schemaLocation="http://schemas.microsoft.com/sqlserver/2004/sqltypes/sqltypes.xsd"/>

<xsd:elementname="Employees">

<xsd:complexType>

<xsd:attributename="EmployeeID"type="sqltypes:int"use="required"/>

<xsd:attributename="FirstName"use="required">

<xsd:simpleType>

<xsd:restrictionbase="sqltypes:nvarchar"sqltypes:localeId="1033"sqltypes:sqlCompareOptions="IgnoreCaseIgnoreKanaTypeIgnoreWidth"sqltypes:sqlSortId="52">

<xsd:maxLengthvalue="10"/>

</xsd:restriction>

</xsd:simpleType>

</xsd:attribute>

<xsd:attributename="LastName"use="required">

<xsd:simpleType>

<xsd:restrictionbase="sqltypes:nvarchar"sqltypes:localeId="1033"sqltypes:sqlCompareOptions="IgnoreCaseIgnoreKanaTypeIgnoreWidth"sqltypes:sqlSortId="52">

<xsd:maxLengthvalue="20"/>

</xsd:restriction>

</xsd:simpleType>

</xsd:attribute>

</xsd:complexType>

</xsd:element>

</xsd:schema>

<Employeesxmlns="urn:schemas-microsoft-com:sql:SqlRowSet1"EmployeeID="1"FirstName="Nancy"LastName="Davolio"/>

<Employeesxmlns="urn:schemas-microsoft-com:sql:SqlRowSet1"EmployeeID="2"FirstName="Andrew"LastName="Fuller"/>

<Employeesxmlns="urn:schemas-microsoft-com:sql:SqlRowSet1"EmployeeID="3"FirstName="Janet"LastName="Leverling"/>

<Employeesxmlns="urn:schemas-microsoft-com:sql:SqlRowSet1"EmployeeID="4"FirstName="Margaret"LastName="Peacock"/>

<Employeesxmlns="urn:schemas-microsoft-com:sql:SqlRowSet1"EmployeeID="5"FirstName="Steven"LastName="Buchanan"/>

<Employeesxmlns="urn:schemas-microsoft-com:sql:SqlRowSet1"EmployeeID="6"FirstName="Michael"LastName="Suyama"/>

<Employeesxmlns="urn:schemas-microsoft-com:sql:SqlRowSet1"EmployeeID="7"FirstName="Robert"LastName="King"/>

<Employeesxmlns="urn:schemas-microsoft-com:sql:SqlRowSet1"EmployeeID="8"FirstName="Laura"LastName="Callahan"/>

<Employeesxmlns="urn:schemas-microsoft-com:sql:SqlRowSet1"EmployeeID="9"FirstName="Anne"LastName="Dodsworth"/>

2、RAW模式

(1).SQL语句：

----将元素命名为自定义的名称Employee

SELECTEmployeeID,FirstName,LastNameFROMEmployeesFORXMLRAW('Employee')

(2).所生成的XML文件：

<EmployeeEmployeeID="1"FirstName="Nancy"LastName="Davolio"/>

<EmployeeEmployeeID="2"FirstName="Andrew"LastName="Fuller"/>

<EmployeeEmployeeID="3"FirstName="Janet"LastName="Leverling"/>

<EmployeeEmployeeID="4"FirstName="Margaret"LastName="Peacock"/>

<EmployeeEmployeeID="5"FirstName="Steven"LastName="Buchanan"/>

<EmployeeEmployeeID="6"FirstName="Michael"LastName="Suyama"/>

<EmployeeEmployeeID="7"FirstName="Robert"LastName="King"/>

<EmployeeEmployeeID="8"FirstName="Laura"LastName="Callahan"/>

<EmployeeEmployeeID="9"FirstName="Anne"LastName="Dodsworth"/>

SELECTEmployeeID"@ID",FirstName"Name/FirstName",LastName"Name/LastName"

FROMEmployeesFORXMLPATH('Employee')

(2).所生成的XML文件

<EmployeeID="1">

<Name>

<FirstName>Nancy</FirstName>

<LastName>Davolio</LastName>

</Name>

</Employee>

<EmployeeID="2">

<Name>

<FirstName>Andrew</FirstName>

<LastName>Fuller</LastName>

</Name>

</Employee>

<EmployeeID="3">

<Name>

<FirstName>Janet</FirstName>

<LastName>Leverling</LastName>

</Name>

</Employee>

<EmployeeID="4">

<Name>

<FirstName>Margaret</FirstName>

<LastName>Peacock</LastName>

</Name>

</Employee>

<EmployeeID="5">

<Name>

<FirstName>Steven</FirstName>

<LastName>Buchanan</LastName>

</Name>

</Employee>

<EmployeeID="6">

<Name>

<FirstName>Michael</FirstName>

<LastName>Suyama</LastName>

</Name>

</Employee>

<EmployeeID="7">

<Name>

<FirstName>Robert</FirstName>

<LastName>King</LastName>

</Name>

</Employee>

<EmployeeID="8">

<Name>

<FirstName>Laura</FirstName>

<LastName>Callahan</LastName>

</Name>

</Employee>

<EmployeeEmpID="1">

<FirstName>Nancy</FirstName>

<LastName>Davolio</LastName>

</Employee>

EXPLICIT模式解决这个问题的应用分为两个主要步骤：

1.定义要输出的XML文档结构；

2.传入实际的数据值；

(1).SQL语句：

--定义输出XML文档的数据结构

SELECT1ASTag,

NULLASParent,

EmployeeIDAS[Employee!1!EmpID],

FirstNameAS[Employee!1!FirstName!element],

LastNameAS[Employee!1!LastName!element]

FROMEmployees

UNIONALL

--传入实际的数据

SELECT1,

NULL,

EmployeeID,

FirstName,

LastName

FROMEmployees

ORDERBY[Employee!1!EmpID],

[Employee!1!FirstName!element],

[Employee!1!LastName!element]

FORXMLEXPLICIT

.csharpcode,.csharpcodepre
{
font-size:small;
color:black;
font-family:consolas,"CourierNew",courier,monospace;
background-color:#ffffff;
/*white-space:pre;*/
}
.csharpcodepre{margin:0em;}
.csharpcode.rem{color:#008000;}
.csharpcode.kwrd{color:#0000ff;}
.csharpcode.str{color:#006080;}
.csharpcode.op{color:#0000c0;}
.csharpcode.preproc{color:#cc6633;}
.csharpcode.asp{background-color:#ffff00;}
.csharpcode.html{color:#800000;}
.csharpcode.attr{color:#ff0000;}
.csharpcode.alt
{
background-color:#f4f4f4;
width:100%;
margin:0em;
}
.csharpcode.lnum{color:#606060;}

.csharpcode,.csharpcodepre
{
font-size:small;
color:black;
font-family:consolas,"CourierNew",courier,monospace;
background-color:#ffffff;
/*white-space:pre;*/
}
.csharpcodepre{margin:0em;}
.csharpcode.rem{color:#008000;}
.csharpcode.kwrd{color:#0000ff;}
.csharpcode.str{color:#006080;}
.csharpcode.op{color:#0000c0;}
.csharpcode.preproc{color:#cc6633;}
.csharpcode.asp{background-color:#ffff00;}
.csharpcode.html{color:#800000;}
.csharpcode.attr{color:#ff0000;}
.csharpcode.alt
{
background-color:#f4f4f4;
width:100%;
margin:0em;
}
.csharpcode.lnum{color:#606060;}

语句含义的解释：

先看看定义XML结构的语句输出结果：

Tag栏用来指定生成元素的嵌套水平；1表示嵌套水平为

Parent栏用来指定当前Tag的父级层次；Null值表示该元素为顶级元素；

EmployeeIDAS[Employee!1!EmpID],

说明：当前元素或属性的父级元素的名称！元素的标签号！元素或属性的名称
FirstNameAS[Employee!1!FirstName!element],

说明：当前元素或属性的父级元素的名称！元素的标签号！元素或属性的名称！指定值作为元素输出

5、为输出的XML文档添加根元素(Rootelement)

(1).SQL语句：

SELECTEmployeeID,FirstName,LastNameFROMEmployeesFORXMLAUTO,ROOT('MyRoot')

<MyRoot>

<EmployeesEmployeeID="1"FirstName="Nancy"LastName="Davolio"/>

<EmployeesEmployeeID="2"FirstName="Andrew"LastName="Fuller"/>

<EmployeesEmployeeID="3"FirstName="Janet"LastName="Leverling"/>

<EmployeesEmployeeID="4"FirstName="Margaret"LastName="Peacock"/>

<EmployeesEmployeeID="5"FirstName="Steven"LastName="Buchanan"/>

<EmployeesEmployeeID="6"FirstName="Michael"LastName="Suyama"/>

<EmployeesEmployeeID="7"FirstName="Robert"LastName="King"/>

<EmployeesEmployeeID="8"FirstName="Laura"LastName="Callahan"/>

<EmployeesEmployeeID="9"FirstName="Anne"LastName="Dodsworth"/>

</MyRoot>

内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理

标签：

相关文章推荐

新的分享

章节导航