DataColumnCollection Class

Definition

Namespace:

System.Data

Assembly:

System.Data.Common.dll

Source:

DataColumnCollection.cs

Represents a collection of DataColumn objects for a DataTable.

public ref class DataColumnCollection sealed : System::Data::InternalDataCollectionBase

public sealed class DataColumnCollection : System.Data.InternalDataCollectionBase

type DataColumnCollection = class
    inherit InternalDataCollectionBase

Public NotInheritable Class DataColumnCollection
Inherits InternalDataCollectionBase

Inheritance

Object

InternalDataCollectionBase

DataColumnCollection

Examples

The following example iterates through a collection of DataColumn objects and prints various properties of each column in the collection.

private void PrintDataTableColumnInfo(DataTable table)
{
    // Use a DataTable object's DataColumnCollection.
    DataColumnCollection columns = table.Columns;

    // Print the ColumnName and DataType for each column.
    foreach(DataColumn column in columns)
    {
        Console.WriteLine(column.ColumnName);
        Console.WriteLine(column.DataType);
    }
}

Private Sub PrintDataTableColumnInfo(table As DataTable)
    
    ' Use a DataTable object's DataColumnCollection.
    Dim columns As DataColumnCollection = table.Columns

    ' Print the ColumnName and DataType for each column.
    Dim column As DataColumn
    For Each column in columns
       Console.WriteLine(column.ColumnName)
       Console.WriteLine(column.DataType.ToString)
    Next
End Sub

Remarks

The DataColumnCollection defines the schema of a DataTable, and determines what kind of data each DataColumn can contain. You can access the DataColumnCollection through the Columns property of the DataTable object.

The DataColumnCollection uses the Add and Remove methods to insert and delete DataColumn objects. Use the Count property to determine how many DataColumn objects are in the collection. Use the Contains method to verify whether a specified index or column name exists in the collection.

Properties

Count	Gets the total number of elements in a collection. (Inherited from InternalDataCollectionBase)
IsReadOnly	Gets a value that indicates whether the InternalDataCollectionBase is read-only. (Inherited from InternalDataCollectionBase)
IsSynchronized	Gets a value that indicates whether the InternalDataCollectionBase is synchronized. (Inherited from InternalDataCollectionBase)
Item[Int32]	Gets the DataColumn from the collection at the specified index.
Item[String]	Gets the DataColumn from the collection with the specified name.
List	Gets the items of the collection as a list. (Inherited from InternalDataCollectionBase)
SyncRoot	Gets an object that can be used to synchronize the collection. (Inherited from InternalDataCollectionBase)

Methods

Add()	Creates and adds a DataColumn object to the DataColumnCollection.
Add(DataColumn)	Creates and adds the specified DataColumn object to the DataColumnCollection.
Add(String)	Creates and adds a DataColumn object that has the specified name to the DataColumnCollection.
Add(String, Type)	Creates and adds a DataColumn object that has the specified name and type to the DataColumnCollection.
Add(String, Type, String)	Creates and adds a DataColumn object that has the specified name, type, and expression to the DataColumnCollection.
AddRange(DataColumn[])	Copies the elements of the specified DataColumn array to the end of the collection.
CanRemove(DataColumn)	Checks whether a specific column can be removed from the collection.
Clear()	Clears the collection of any columns.
Contains(String)	Checks whether the collection contains a column with the specified name.
CopyTo(Array, Int32)	Copies all the elements of the current InternalDataCollectionBase to a one-dimensional Array, starting at the specified InternalDataCollectionBase index. (Inherited from InternalDataCollectionBase)
CopyTo(DataColumn[], Int32)	Copies the entire collection into an existing array, starting at a specified index within the array.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetEnumerator()	Gets an IEnumerator for the collection. (Inherited from InternalDataCollectionBase)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
IndexOf(DataColumn)	Gets the index of a column specified by name.
IndexOf(String)	Gets the index of the column with the specific name (the name is not case sensitive).
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
Remove(DataColumn)	Removes the specified DataColumn object from the collection.
Remove(String)	Removes the DataColumn object that has the specified name from the collection.
RemoveAt(Int32)	Removes the column at the specified index from the collection.
ToString()	Returns a string that represents the current object. (Inherited from Object)

Events

CollectionChanged

Occurs when the columns collection changes, either by adding or removing a column.

Extension Methods

Cast<TResult>(IEnumerable)	Casts the elements of an IEnumerable to the specified type.
OfType<TResult>(IEnumerable)	Filters the elements of an IEnumerable based on a specified type.
AsParallel(IEnumerable)	Enables parallelization of a query.
AsQueryable(IEnumerable)	Converts an IEnumerable to an IQueryable.

Thread Safety

This type is safe for multithreaded read operations. You must synchronize any write operations.

See also

• Columns
• DataColumn
• DataTable
• DataRelation
• DataRow
• DataSet