Nilai Kolom SQL XML
SQL Server mendukung jenis data xml, dan pengembang dapat mengambil kumpulan hasil termasuk jenis ini menggunakan perilaku standar kelas SqlCommand. Kolom xml dapat diambil sama seperti kolom apa pun yang diambil (ke dalam SqlDataReader, misalnya) tetapi jika Anda ingin bekerja dengan konten kolom sebagai XML, Anda harus menggunakan XmlReader.
Contoh
Aplikasi konsol berikut memilih dua baris, masing-masing berisi kolom xml, dari tabel Sales.Store di database AdventureWorks ke instans SqlDataReader. Untuk setiap baris, nilai kolom xml dibaca menggunakan metode GetSqlXml dari SqlDataReader. Nilai disimpan dalam XmlReader. Perhatikan bahwa Anda harus menggunakan GetSqlXml bukan metode GetValue jika Anda ingin mengatur konten ke variabel SqlXml; GetValue mengembalikan nilai kolom xml sebagai string.
Catatan
Basis data contoh AdventureWorks tidak diinstal secara default saat Anda menginstal SQL Server. Anda dapat menginstalnya dengan menjalankan Penyetelan SQL Server.
// Example assumes the following directives:
// using System.Data.SqlClient;
// using System.Xml;
// using System.Data.SqlTypes;
static void GetXmlData(string connectionString)
{
using (SqlConnection connection = new(connectionString))
{
connection.Open();
// The query includes two specific customers for simplicity's
// sake. A more realistic approach would use a parameter
// for the CustomerID criteria. The example selects two rows
// in order to demonstrate reading first from one row to
// another, then from one node to another within the xml column.
const string commandText =
"SELECT Demographics from Sales.Store WHERE " +
"CustomerID = 3 OR CustomerID = 4";
SqlCommand commandSales = new(commandText, connection);
SqlDataReader salesReaderData = commandSales.ExecuteReader();
// Multiple rows are returned by the SELECT, so each row
// is read and an XmlReader (an xml data type) is set to the
// value of its first (and only) column.
var countRow = 1;
while (salesReaderData.Read())
// Must use GetSqlXml here to get a SqlXml type.
// GetValue returns a string instead of SqlXml.
{
SqlXml salesXML =
salesReaderData.GetSqlXml(0);
XmlReader salesReaderXml = salesXML.CreateReader();
Console.WriteLine("-----Row " + countRow + "-----");
// Move to the root.
salesReaderXml.MoveToContent();
// We know each node type is either Element or Text.
// All elements within the root are string values.
// For this simple example, no elements are empty.
while (salesReaderXml.Read())
{
if (salesReaderXml.NodeType == XmlNodeType.Element)
{
var elementLocalName =
salesReaderXml.LocalName;
salesReaderXml.Read();
Console.WriteLine(elementLocalName + ": " +
salesReaderXml.Value);
}
}
countRow++;
}
}
}
' Example assumes the following directives:
' Imports System.Data.SqlClient
' Imports System.Xml
' Imports System.Data.SqlTypes
Private Sub GetXmlData(ByVal connectionString As String)
Using connection As SqlConnection = New SqlConnection(connectionString)
connection.Open()
'The query includes two specific customers for simplicity's
'sake. A more realistic approach would use a parameter
'for the CustomerID criteria. The example selects two rows
'in order to demonstrate reading first from one row to
'another, then from one node to another within the xml
'column.
Dim commandText As String = _
"SELECT Demographics from Sales.Store WHERE " & _
"CustomerID = 3 OR CustomerID = 4"
Dim commandSales As New SqlCommand(commandText, connection)
Dim salesReaderData As SqlDataReader = commandSales.ExecuteReader()
' Multiple rows are returned by the SELECT, so each row
' is read and an XmlReader (an xml data type) is set to the
' value of its first (and only) column.
Dim countRow As Integer = 1
While salesReaderData.Read()
' Must use GetSqlXml here to get a SqlXml type.
' GetValue returns a string instead of SqlXml.
Dim salesXML As SqlXml = _
salesReaderData.GetSqlXml(0)
Dim salesReaderXml As XmlReader = salesXML.CreateReader()
Console.WriteLine("-----Row " & countRow & "-----")
' Move to the root.
salesReaderXml.MoveToContent()
' We know each node type is either Element or Text.
' All elements within the root are string values.
' For this simple example, no elements
' are empty.
While salesReaderXml.Read()
If salesReaderXml.NodeType = XmlNodeType.Element Then
Dim elementLocalName As String = _
salesReaderXml.LocalName
salesReaderXml.Read()
Console.WriteLine(elementLocalName & ": " & _
salesReaderXml.Value)
End If
End While
countRow = countRow + 1
End While
End Using
End Sub