SQL2005CLR函数扩展-天气服务

我们可以用CLR获取网络服务 来显示到数据库自定函数的结果集中，比如163的天气预报

http://news.163.com/xml/weather.xml

他的这个xml结果的日期是不正确的，但这个我们暂不讨论。

从这个xml获取天气的CLR代码如下，用WebClient访问一下就可以了。然后通过Dom对象遍历节点属性返回给结果集。

using

System;

using

System.Data;

using

System.Data.SqlClient;

using

System.Data.SqlTypes;

using

System.Collections;

using

System.Collections.Generic;

using

Microsoft.SqlServer.Server;

public
partial
class
UserDefinedFunctions

{

[SqlFunction
(TableDefinition = "city nvarchar(100),date nvarchar(100),general
nvarchar(100),temperature nvarchar(100),wind nvarchar(100)"
, Name =
"GetWeather"
, FillRowMethodName = "FillRow"
)]

public
static
IEnumerable
GetWeather()

{

System.Collections.Generic.List
<Item
> list = GetData();

return
list;

}

public
static
void
FillRow(Object
obj, out
SqlString
city, out
SqlString
date, out
SqlString
general, out
SqlString
temperature, out
SqlString
wind)

{

Item
data = (Item
)obj;

city = data.city;

date = data.date;

general = data.general;

temperature = data.temperature;

wind = data.wind;

}

class
Item

{

public
string
city;

public
string
date;

public
string
general;

public
string
temperature;

public
string
wind;

}

static
System.Collections.Generic.List
<Item
>
GetData()

{

System.Collections.Generic.List
<Item
> ret = new
List
<Item
>();

//try

//{

string
url = "http://news.163.com/xml/weather.xml"
;

System.Net.WebClient
wb = new
System.Net.WebClient
();

byte
[]
b = wb.DownloadData(url);

string
data = System.Text.Encoding
.Default.GetString(b);

System.Xml.XmlDocument
doc = new
System.Xml.XmlDocument
();

doc.LoadXml(data);

foreach
(System.Xml.XmlNode
node in
doc.ChildNodes[1])

{

string
city = GetXMLAttrib(node, "name"
);

foreach
(System.Xml.XmlNode
subnode in
node.ChildNodes)

{

Item
item = new
Item
();

item.city = city;

item.date =
GetXMLAttrib(subnode, "date"
);

item.general =
GetXMLAttrib(subnode, "general"
);

item.temperature =
GetXMLAttrib(subnode, "temperature"
);

item.wind =
GetXMLAttrib(subnode, "wind"
);

ret.Add(item);

}

}

//}

//catch(Exception ex)

//{

//

SqlContext.Pipe.Send(ex.Message);

//}

return
ret;

}

static
string
GetXMLAttrib(System.Xml.XmlNode
node, string
attrib)

{

try

{

return
node.Attributes[attrib].Value;

}

catch

{

return
string
.Empty;

}

}

};

部署这个clr函数的脚本如下

drop
function
dbo.
xfn_GetWeather

drop

ASSEMBLY
TestWeather

go

CREATE
ASSEMBLY
TestWeather FROM
'd:/sqlclr/TestWeather.dll'
WITH
PERMISSION_SET =
UnSAFE;

--

go

CREATE
FUNCTION
dbo.
xfn_GetWeather ()

RETURNS
table
(
city nvarchar
(
100),
date nvarchar
(
100),
general nvarchar
(
100),
temperature nvarchar
(
100),
wind nvarchar
(
100))

AS
EXTERNAL
NAME
TestWeather.
UserDefinedFunctions.
GetWeather

测试函数

select
*
from
dbo.
xfn_GetWeather
()