Writes the current data structure of the DataTable as an XML schema using the specified TextWriter. To save the schema for the table and all its descendants, set the writeHierarchy parameter to true.
Assembly: System.Data (in System.Data.dll)
Syntax
Public Sub WriteXmlSchema ( _
writer As TextWriter, _
writeHierarchy As Boolean _
)public void WriteXmlSchema(
TextWriter writer,
bool writeHierarchy
)public:
void WriteXmlSchema(
TextWriter^ writer,
bool writeHierarchy
)member WriteXmlSchema :
writer:TextWriter *
writeHierarchy:bool -> unit
Parameters
- writer
- Type: System.IO
. . :: . TextWriter
The TextWriter with which to write.
- writeHierarchy
- Type: System
. . :: . Boolean
If true, write the schema of the current table and all its descendants. If false (the default value), write the schema for the current table only.
Remarks
Use the WriteXmlSchema method to write the schema for a DataTable to an XML document. The schema includes table, relation, and constraint definitions.
The XML schema is written using the XSD standard.
To write the data to an XML document, use the WriteXml method.
Normally the WriteXmlSchema method writes the schema only for the current table. To write the schema for the current table and its entire descendant, related tables, call the method with the writeHierarchy parameter set to true.
Examples
The following console application creates two DataTable instances, adds each to a DataSet, creates a DataRelation relating the two tables, and then uses the WriteXmlSchema method to write the data contained within the parent table to a TextWriter. The example demonstrates the behavior when setting the writeHierarchy parameter to each of its values.
Sub Main()
Dim ds As New DataSet
Dim customerTable As DataTable = GetCustomers()
Dim orderTable As DataTable = GetOrders()
ds.Tables.Add(customerTable)
ds.Tables.Add(orderTable)
ds.Relations.Add("CustomerOrder", _
New DataColumn() {customerTable.Columns(0)}, _
New DataColumn() {orderTable.Columns(1)}, True)
Dim writer As New System.IO.StringWriter
customerTable.WriteXmlSchema(writer, False)
PrintOutput(writer, "Customer table, without hierarchy")
writer = New System.IO.StringWriter
customerTable.WriteXmlSchema(writer, True)
PrintOutput(writer, "Customer table, with hierarchy")
Console.WriteLine("Press any key to continue.")
Console.ReadKey()
End Sub
Private Function GetOrders() As DataTable
' Create sample Customers table, in order
' to demonstrate the behavior of the DataTableReader.
Dim table As New DataTable
' Create three columns, OrderID, CustomerID, and OrderDate.
table.Columns.Add(New DataColumn("OrderID", GetType(System.Int32)))
table.Columns.Add(New DataColumn("CustomerID", GetType(System.Int32)))
table.Columns.Add(New DataColumn("OrderDate", GetType(System.DateTime)))
' Set the OrderID column as the primary key column.
table.PrimaryKey = New DataColumn() {table.Columns(0)}
table.Rows.Add(New Object() {1, 1, #12/2/2003#})
table.Rows.Add(New Object() {2, 1, #1/3/2004#})
table.Rows.Add(New Object() {3, 2, #11/13/2004#})
table.Rows.Add(New Object() {4, 3, #5/16/2004#})
table.Rows.Add(New Object() {5, 3, #5/22/2004#})
table.Rows.Add(New Object() {6, 4, #6/15/2004#})
table.AcceptChanges()
Return table
End Function
Private Function GetCustomers() As DataTable
' Create sample Customers table, in order
' to demonstrate the behavior of the DataTableReader.
Dim table As New DataTable
' Create two columns, ID and Name.
Dim idColumn As DataColumn = table.Columns.Add("ID", _
GetType(System.Int32))
table.Columns.Add("Name", GetType(System.String))
' Set the ID column as the primary key column.
table.PrimaryKey = New DataColumn() {idColumn}
table.Rows.Add(New Object() {1, "Mary"})
table.Rows.Add(New Object() {2, "Andy"})
table.Rows.Add(New Object() {3, "Peter"})
table.Rows.Add(New Object() {4, "Russ"})
table.AcceptChanges()
Return table
End Function
Private Sub PrintOutput( _
ByVal writer As System.IO.TextWriter, ByVal caption As String)
Console.WriteLine("==============================")
Console.WriteLine(caption)
Console.WriteLine("==============================")
Console.WriteLine(writer.ToString())
End Sub
static void Main()
{
DataSet ds = new DataSet();
DataTable customerTable = GetCustomers();
DataTable orderTable = GetOrders();
ds.Tables.Add(customerTable);
ds.Tables.Add(orderTable);
ds.Relations.Add("CustomerOrder",
new DataColumn[] { customerTable.Columns[0] },
new DataColumn[] { orderTable.Columns[1] }, true);
System.IO.StringWriter writer = new System.IO.StringWriter();
customerTable.WriteXmlSchema(writer, false);
PrintOutput(writer, "Customer table, without hierarchy");
writer = new System.IO.StringWriter();
customerTable.WriteXmlSchema(writer, true);
PrintOutput(writer, "Customer table, with hierarchy");
Console.WriteLine("Press any key to continue.");
Console.ReadKey();
}
private static DataTable GetCustomers()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID", typeof(System.Int32));
table.Columns.Add("Name", typeof(System.String));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { 1, "Mary" });
table.Rows.Add(new object[] { 2, "Andy" });
table.Rows.Add(new object[] { 3, "Peter" });
table.Rows.Add(new object[] { 4, "Russ" });
table.AcceptChanges();
return table;
}
private static DataTable GetOrders()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create three columns; OrderID, CustomerID, and OrderDate.
table.Columns.Add(new DataColumn("OrderID", typeof(System.Int32)));
table.Columns.Add(new DataColumn("CustomerID", typeof(System.Int32)));
table.Columns.Add(new DataColumn("OrderDate", typeof(System.DateTime)));
// Set the OrderID column as the primary key column.
table.PrimaryKey = new DataColumn[] { table.Columns[0] };
table.Rows.Add(new object[] { 1, 1, "12/2/2003" });
table.Rows.Add(new object[] { 2, 1, "1/3/2004" });
table.Rows.Add(new object[] { 3, 2, "11/13/2004" });
table.Rows.Add(new object[] { 4, 3, "5/16/2004" });
table.Rows.Add(new object[] { 5, 3, "5/22/2004" });
table.Rows.Add(new object[] { 6, 4, "6/15/2004" });
table.AcceptChanges();
return table;
}
private static void PrintOutput(System.IO.TextWriter writer, string caption)
{
Console.WriteLine("==============================");
Console.WriteLine(caption);
Console.WriteLine("==============================");
Console.WriteLine(writer.ToString());
}
The example displays the following output in the console window:
==============================
Customer table, without hierarchy
==============================
<?xml version="1.0" encoding="utf-16"?>
<xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
<xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:MainDataTable="Ta
ble1">
<xs:complexType>
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:element name="Table1">
<xs:complexType>
<xs:sequence>
<xs:element name="ID" type="xs:int" />
<xs:element name="Name" type="xs:string" minOccurs="0" />
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:choice>
</xs:complexType>
<xs:unique name="Constraint1" msdata:PrimaryKey="true">
<xs:selector xpath=".//Table1" />
<xs:field xpath="ID" />
</xs:unique>
</xs:element>
</xs:schema>
==============================
Customer table, with hierarchy
==============================
<?xml version="1.0" encoding="utf-16"?>
<xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
<xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:MainDataTable="Table1">
<xs:complexType>
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:element name="Table1">
<xs:complexType>
<xs:sequence>
<xs:element name="ID" type="xs:int" />
<xs:element name="Name" type="xs:string" minOccurs="0" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="Table2">
<xs:complexType>
<xs:sequence>
<xs:element name="OrderID" type="xs:int" />
<xs:element name="CustomerID" type="xs:int" minOccurs="0" />
<xs:element name="OrderDate" type="xs:dateTime" minOccurs="0" />
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:choice>
</xs:complexType>
<xs:unique name="Constraint1" msdata:PrimaryKey="true">
<xs:selector xpath=".//Table1" />
<xs:field xpath="ID" />
</xs:unique>
<xs:unique name="Table2_Constraint1" msdata:ConstraintName="Constraint1" msdata:PrimaryKey="true">
<xs:selector xpath=".//Table2" />
<xs:field xpath="OrderID" />
</xs:unique>
<xs:keyref name="CustomerOrder" refer="Constraint1">
<xs:selector xpath=".//Table2" />
<xs:field xpath="CustomerID" />
</xs:keyref>
</xs:element>
</xs:schema> Platforms
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements. See Also
