浅析.NET下XML数据访问新机制

        using System;
using System.Data;
using System.Data.SqlClient;
using System.Text;
using System.Xml;
using Microsoft.Data.SqlXml;

        public string ExecuteADONetSelect(string CustomerID, 
string ConnectionString)
{
// 创建一个数据库连接对象
SqlConnection myConnection = new SqlConnection(ConnectionString);
// 创建一个数据适配器对象
SqlDataAdapter mySqlDataAdapter1 = new SqlDataAdapter("SELECT *
FROM customers WHERE CustomerID = @CustomerID", myConnection);
// 为其参数集添加参数 
mySqlDataAdapter1.SelectCommand.Parameters.Add("@CustomerID",
SqlDbType.Char, 5, "CustomerID");
mySqlDataAdapter1.SelectCommand.Parameters["@CustomerID"].
Value = CustomerID;
// 创建一个数据集对象
DataSet myDataSet = new DataSet();
// 运用数据集对象的Fill方法来填充数据集对象
mySqlDataAdapter1.Fill(myDataSet,"Customers");
// 关闭数据库连接
myConnection.Close();
// 返回数据集对象中的数据的XML形式
return myDataSet.GetXml();
}

        public string ExecuteSqlDataReaderSelect(string CustomerID, 
string ConnectionString)
{ 
SqlDataReader myDataReader = null;
// 创建一个数据库连接对象
SqlConnection mySqlConnection = new SqlConnection
(ConnectionString);
// 创建一个数据库命令对象，并在SQL语句中运用FOR XML子句
SqlCommand mySqlCommand = new SqlCommand("SELECT * FROM Customers 
WHERE CustomerID = @CustomerID FOR XML RAW", mySqlConnection);
mySqlCommand.CommandType = CommandType.Text;
// 为其参数集添加参数
mySqlCommand.Parameters.Add("@CustomerID", SqlDbType.Char, 5,
"CustomerID");
mySqlCommand.Parameters["@CustomerID"].Value = CustomerID;
mySqlConnection.Open();
// 执行数据库命令对象的ExecuteReader操作以取得一个数据阅读器对象
myDataReader = mySqlCommand.ExecuteReader(CommandBehavior.
CloseConnection);
// 创建一个StringBuilder对象以构造XML字符串
StringBuilder xml = new StringBuilder(8192);
// 不断从数据阅读器中获取XML数据并添加到StringBuilder对象中
while (myDataReader.Read())
{
if (!myDataReader.IsDBNull(0))
xml.Append(myDataReader.GetString(0));
}
myDataReader.Close();
mySqlConnection.Close();
// 返回XML数据的字符串形式
return xml.ToString();
}

        public string ExecuteSqlXmlSelect(string CustomerID, string
ConnectionString, bool ClientSide)
{
// 创建一个SqlXmlCommand对象
SqlXmlCommand cmd = new SqlXmlCommand(ConnectionString);
cmd.RootTag = "Customers";
cmd.ClientSideXml = ClientSide;
cmd.CommandText = "SELECT * FROM Customers WHERE CustomerID =
'" + CustomerID + "' FOR XML RAW";
// 执行SqlXmlCommand对象的ExecuteXmlReader操作以取得一个XmlReader对象
XmlReader xr = cmd.ExecuteXmlReader();
// 创建一个XmlDocument对象
XmlDocument xd = new XmlDocument();
// 运用其Load方法将获取的XML数据载入到一个DOM中并返回XML数据的字符串形式
xd.Load(xr);
return xd.OuterXml
}

        Public Function ExecuteSelect(
CustomerID As String,
ConnectionString As String) 
As String
Set conn = New ADODB.Connection
conn.ConnectionString = ConnectionString
conn.Open
Set cmd = New ADODB.Command
cmd.ActiveConnection = conn
cmd.CommandText = "select * from customers 
where CustomerID = '" & CustomerID & "'" 
Set rs = cmd.Execute
Set adoStream = New ADODB.Stream
adoStream.Type = adTypeText
adoStream.Open    
rs.Save adoStream, adPersistXML
'返回XML字符串
ExecuteSelect = adoStream.ReadText()
End Function