SQL XML 열 값

SQL Server는 xml 데이터 형식을 지원하며 개발자는 SqlCommand 클래스의 표준 동작을 사용하여 이 형식을 포함하는 결과 집합을 검색할 수 있습니다. xml 열은 다른 열과 마찬가지 방식으로 검색할 수 있지만(예: SqlDataReader로) 열의 내용을 XML로 작업하려면 XmlReader를 사용해야 합니다.

예시

다음 콘솔 애플리케이션에서는 AdventureWorks 데이터베이스의 Sales.Store 테이블에서 SqlDataReader 인스턴스까지 각각 xml 열이 포함된 두 개의 행을 선택합니다. 각 행에서 xml 열의 값은 GetSqlXml의 SqlDataReader 메서드를 사용하여 읽습니다. 값은 XmlReader에 저장되어 있습니다. GetSqlXml는 GetValue 열의 값을 문자열로 반환하므로 내용을 SqlXml 변수로 설정하려면 GetValue 메서드보다는 xml을 사용해야 합니다.

// 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

참고 항목

• SqlXml
• SQL Server의 XML 데이터
• ADO.NET 개요