DataColumn Constructores

public:
 DataColumn();

public DataColumn ();

Public Sub New ()

Ejemplos

En el ejemplo siguiente se crea un nuevo DataColumn , se establecen varias propiedades y se agrega a DataColumnCollection para el DataTable objeto.The following example creates a new DataColumn, sets various properties, and adds it to a DataColumnCollection for the DataTable object.

private void AddDataColumn(DataTable table)
{
    DataColumn column = new DataColumn();

    // Set various properties.
    column.ColumnName = "id";
    column.DataType = System.Type.GetType("System.Int32");
    column.AutoIncrement = true;
    column.AutoIncrementSeed = 1;
    column.AutoIncrementStep = 1;
    column.ReadOnly = true;

    // Add to Columns collection.
    table.Columns.Add(column);
}

Private Sub AddDataColumn(ByVal table As DataTable)
    Dim column As New DataColumn()

    ' Set various properties.
    With column
       .ColumnName = "id"
       .DataType = System.Type.GetType("System.Int32")
       .AutoIncrement = True
       .AutoIncrementSeed = 1
       .AutoIncrementStep = 1
       .ReadOnly = True
     End With

    ' Add to Columns collection.
    table.Columns.Add(column)
End Sub

Comentarios

Cuando se crea, un DataColumn objeto no tiene ningún valor predeterminado ColumnName o Caption .When created, a DataColumn object has no default ColumnName or Caption. Cuando se agrega a un DataColumnCollection , se generará un nombre predeterminado ("Column1", "columna2", etc.) si no se ha asignado un nombre a ColumnName .When you add it to a DataColumnCollection, a default name ("Column1", "Column2", and so on) will be generated if a name has not been assigned to the ColumnName.

Consulte también

• ColumnName
• Caption
• DefaultValue
• DataTable
• DataType
• Usar conjuntos de valores en ADO.NETUsing DataSets in ADO.NET

public:
 DataColumn(System::String ^ columnName);

public DataColumn (string? columnName);

public DataColumn (string columnName);

new System.Data.DataColumn : string -> System.Data.DataColumn

Public Sub New (columnName As String)

Parámetros

Ejemplos

En el ejemplo siguiente se crea un nuevo DataColumn con un especificado ColumnName .The following example creates a new DataColumn with a specified ColumnName.

private void AddDataColumn(DataTable table)
{
    DataColumn column = new DataColumn("id");

    // Set various properties.
    column.DataType = System.Type.GetType("System.Int32");
    column.AutoIncrement = true;
    column.AutoIncrementSeed = 1;
    column.AutoIncrementStep = 1;
    column.ReadOnly = true;

    // Add to Columns collection.
    table.Columns.Add(column);
}

Private Sub AddDataColumn(ByVal table As DataTable)
    Dim column As DataColumn 
    column = New DataColumn("id")

    ' Set various properties.
    With column
       .DataType = System.Type.GetType("System.Int32")
       .AutoIncrement = True
       .AutoIncrementSeed = 1
       .AutoIncrementStep = 1
       .ReadOnly = True
     End With

    ' Add to Columns collection.
    table.Columns.Add(column)
End Sub

Comentarios

De forma predeterminada, el nombre específico de una columna se convierte en el Caption valor de propiedad.By default, the name specific to a column becomes the Caption property value.

Consulte también

• ColumnName
• Caption
• DefaultValue
• DataTable
• DataType
• Usar conjuntos de valores en ADO.NETUsing DataSets in ADO.NET

public:
 DataColumn(System::String ^ columnName, Type ^ dataType);

public DataColumn (string? columnName, Type dataType);

public DataColumn (string columnName, Type dataType);

new System.Data.DataColumn : string * Type -> System.Data.DataColumn

Public Sub New (columnName As String, dataType As Type)

Parámetros

Excepciones

Ejemplos

En el ejemplo siguiente se crea un nuevo DataColumn con un y un especificados ColumnName DataType .The following example creates a new DataColumn with a specified ColumnName and DataType.

private void AddDataColumn(DataTable table)
{
    System.Type typeInt32 =
        System.Type.GetType("System.Int32");
    DataColumn column = new DataColumn("id", typeInt32);

    // Set various properties.
    column.AutoIncrement = true;
    column.AutoIncrementSeed = 1;
    column.AutoIncrementStep = 1;
    column.ReadOnly = true;

    // Add to Columns collection.
    table.Columns.Add(column);
}

Private Sub AddDataColumn(ByVal table As DataTable)
    
   Dim typeInt32 As System.Type = _
      System.Type.GetType("System.Int32")
   Dim column As DataColumn = _
       New DataColumn("id", typeInt32)

   ' Set various properties.
   With column
      .AutoIncrement = True
      .AutoIncrementSeed = 1
      .AutoIncrementStep = 1
      .ReadOnly = True
    End With

   ' Add to Columns collection.
   table.Columns.Add(column)
End Sub

Consulte también

• DefaultValue
• ColumnName
• Caption
• DataTable
• DataType
• Usar conjuntos de valores en ADO.NETUsing DataSets in ADO.NET

public:
 DataColumn(System::String ^ columnName, Type ^ dataType, System::String ^ expr);

public DataColumn (string? columnName, Type dataType, string? expr);

public DataColumn (string columnName, Type dataType, string expr);

new System.Data.DataColumn : string * Type * string -> System.Data.DataColumn

Public Sub New (columnName As String, dataType As Type, expr As String)

Parámetros

Excepciones

Ejemplos

En el ejemplo siguiente se crea una columna calculada.The following example creates a computed column.

private void AddDataColumn(DataTable table)
{
    System.Type decimalType;
    decimalType = System.Type.GetType("System.Decimal");

    // Create the column. The name is 'Tax,' with data type Decimal,and
    // an expression ('UnitPrice * .0862) to calculate the tax.
    DataColumn column = new DataColumn("Tax",
        decimalType, "UnitPrice * .0862");

    // Set various properties.
    column.AutoIncrement = false;
    column.ReadOnly = true;

    // Add to Columns collection.;
    table.Columns.Add(column);
}

Private Sub AddDataColumn(ByVal table As DataTable)
    Dim column As DataColumn 
    Dim decimalType As System.Type
 
    decimalType = System.Type.GetType("System.Decimal")
    column = New DataColumn("Tax", decimalType, "UnitPrice * .0862")

    ' Set various properties.
    With column
       .AutoIncrement = False
       .ReadOnly = True
    End With

    ' Add to Columns collection.
    table.Columns.Add(column)
 End Sub

Consulte también

• DefaultValue
• ColumnName
• Caption
• DataTable
• DataType
• Expression
• Usar conjuntos de valores en ADO.NETUsing DataSets in ADO.NET

public:
 DataColumn(System::String ^ columnName, Type ^ dataType, System::String ^ expr, System::Data::MappingType type);

public DataColumn (string? columnName, Type dataType, string? expr, System.Data.MappingType type);

public DataColumn (string columnName, Type dataType, string expr, System.Data.MappingType type);

new System.Data.DataColumn : string * Type * string * System.Data.MappingType -> System.Data.DataColumn

Public Sub New (columnName As String, dataType As Type, expr As String, type As MappingType)

Parámetros

Excepciones

Ejemplos

En el ejemplo siguiente se crea una columna calculada.The following example constructs a computed column.

private void CreateComputedColumn(DataTable table)
{
    System.Type myDataType =
        System.Type.GetType("System.Decimal");

    // The expression multiplies the "Price" column value
    // by the "Quantity" to create the "Total" column.
    string expression = "Price * Quantity";

    // Create the column, setting the type to Attribute.
    DataColumn column = new DataColumn("Total", myDataType,
        expression, MappingType.Attribute);

    // Set various properties.
    column.AutoIncrement = false;
    column.ReadOnly = true;

    // Add the column to a DataTable object's to DataColumnCollection.
    DataSet1.Tables["OrderDetails"].Columns.Add(column);
}

Private Sub CreateComputedColumn(ByVal table As DataTable)
    Dim column As DataColumn
    Dim decimalType As System.Type = _
        System.Type.GetType("System.Decimal")

    ' The expression multiplies the "Price" column value by the 
    ' "Quantity" to create the "Total" column.
    Dim expression As String = "Price * Quantity"

    ' Create the column, setting the type to Attribute.
    column = New DataColumn("Total", decimalType, _
        expression, MappingType.Attribute)

    ' Set various properties.
    column.AutoIncrement = False
    column.ReadOnly = True

    ' Add the column to a DataTable object's DataColumnCollection.
    DataSet1.Tables("OrderDetails").Columns.Add(column)
End Sub

Comentarios

El type argumento establece la ColumnMapping propiedad.The type argument sets the ColumnMapping property. La propiedad especifica cómo DataColumn se asigna un cuando DataSet se transforma en un documento XML.The property specifies how a DataColumn is mapped when a DataSet is transformed into an XML document. Por ejemplo, si la columna se denomina "fName" y el valor que contiene es "Bob", y type está establecido en MappingType.Attribute , el elemento XML sería como sigue:For example, if the column is named "fName," and the value it contains is "Bob," and type is set to MappingType.Attribute, the XML element would be as follows:

<Name fName = 'Bob'/>

Para obtener más información sobre cómo se asignan las columnas a elementos o atributos, vea la ColumnMapping propiedad.For more information about how columns are mapped to elements or attributes, see the ColumnMapping property.

Consulte también

• ColumnName
• ColumnMapping
• Caption
• DefaultValue
• DataTable
• DataType
• Usar conjuntos de valores en ADO.NETUsing DataSets in ADO.NET