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DataColumn Constructor (String, Type, String)

Initializes a new instance of the DataColumn class using the specified name, data type, and expression.

Namespace: System.Data
Assembly: System.Data (in system.data.dll)

public DataColumn (
	string columnName,
	Type dataType,
	string expr
)
public DataColumn (
	String columnName, 
	Type dataType, 
	String expr
)
public function DataColumn (
	columnName : String, 
	dataType : Type, 
	expr : String
)

Parameters

columnName

A string that represents the name of the column to be created. If set to a null reference (Nothing in Visual Basic) or an empty string (""), a default name will be specified when added to the columns collection.

dataType

A supported DataType.

expr

The expression used to create this column. For more information, see the Expression property.

Exception typeCondition

ArgumentNullException

No dataType was specified.

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);


Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0
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