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SQL XML-oszlopértékek

SQL Server támogatja a(z) xml adattípust. A SqlCommand osztály használatával lekérheti az ilyen típust tartalmazó eredményhalmazokat. Az SqlDataReader oszlopokat a xml segítségével kérheti le, a többi oszlophoz hasonlóan. Ha XML-ként szeretne dolgozni a tartalmukkal, használja a XmlReader.

példa

Az alábbi konzolalkalmazás két sort jelöl ki a(z) AdventureWorks adatbázisban lévő Sales.Store táblából, amelyek mindegyike egy xml oszlopot tartalmaz. Minden sor esetében a kód meghívja a GetSqlXml-t, és a CreateReader() használatával hozza létre a XmlReader-t. Ha ehelyett meg szeretné őrizni az értéket mint SqlXml, használja közvetlenül a(z) GetSqlXml által visszaadott értéket. A GetValue metódus sztringként adja vissza az xml oszlop értékét.

Megjegyzés:

A AdventureWorks mintaadatbázis alapértelmezés szerint nincs telepítve az SQL Server telepítésekor. Az SQL Server telepítőjének futtatásával telepítheti.

// Example assumes the following directives:
//     using Microsoft.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 Microsoft.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

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