แก้ไข

แชร์ผ่าน

DataColumnCollection.CanRemove(DataColumn) Method

  • Reference

Definition

Namespace:
System.Data
Assembly:
System.Data.Common.dll
Assembly:
System.Data.dll
Assembly:
netstandard.dll
Source:
DataColumnCollection.cs
Source:
DataColumnCollection.cs
Source:
DataColumnCollection.cs

Checks whether a specific column can be removed from the collection.

public:
 bool CanRemove(System::Data::DataColumn ^ column);
public bool CanRemove (System.Data.DataColumn? column);
public bool CanRemove (System.Data.DataColumn column);
member this.CanRemove : System.Data.DataColumn -> bool
Public Function CanRemove (column As DataColumn) As Boolean

Parameters

column
DataColumn

A DataColumn in the collection.

Returns

Boolean

true if the column can be removed. false if,

  • The column parameter is null.

  • The column does not belong to this collection.

  • The column is part of a relationship.

  • Another column's expression depends on this column.

Exceptions

ArgumentNullException

The column parameter is null.

ArgumentException

The column does not belong to this collection.

-or-

The column is part of a relationship.

-or-

Another column's expression depends on this column.

Examples

The following example first uses the Contains method to determine whether a particular column is found in the collection. If found, the CanRemove method tests whether the column can be removed. If so, the column is removed with the Remove method.

private void RemoveColumn(string columnName, DataTable table)
{
    DataColumnCollection columns = table.Columns;
    if (columns.Contains(columnName))
        if (columns.CanRemove(columns[columnName]))
            columns.Remove(columnName);
}

Private Sub RemoveColumn( _
    columnName As String, table As DataTable)

    Dim columns As DataColumnCollection = table.Columns
    If columns.Contains(columnName) Then 
        If columns.CanRemove(columns(columnName)) Then 
           columns.Remove(columnName)
        End If
    End If
End Sub

Remarks

The CanRemove method performs several checks before returning a true or false result. This includes the following: whether the column exists, belongs to the table, or is involved in a constraint or relation.

Use the CanRemove method before you try to remove any column from a collection. You can also use the Contains method to determine whether a particular column exists before you try to remove it.

Applies to

See also