Setting the DataColumn.DataType value is very important to guaranteeing the correct creation and updating of data in a data source.

The DataColumn.DataType property supports the following base .NET Framework data types:

• bool

• byte

• char

• DateTime

• decimal

• double

• Guid

• short

• int

• long

• sbyte

• float

• string

• TimeSpan

• ushort

• uint

• ulong

as well as the following array type:

• Byte[]

An exception is generated when changing this property after the column has begun storing data.

If DataColumn.AutoIncrement is set to true before setting the DataColumn.DataType property, and you try to set the type to anything except an integer type, an exception is generated.

byte[] columnValue = (byte[])myDataTable.Rows[0][0];
byte[] newValue = (byte[])columnValue.Clone();
newValue[1] = 2;
myDataTable.Rows[0][0] = newValue;

• The column cannot be part of a DataView.RowFilter or DataTable.Select expression.

• If the column is used as a DataTable.PrimaryKey, or as a DataView.Sort or for a System.Data.DataView, it must be treated as an immutable field; the column data must not be changed once it has been added to the table.

• Its DataColumn.ColumnMapping can be only set to MappingType.Element.

• The class that implements the column’s data type must be must be marked with the SerializableAttribute, and if necessary implement the System.Runtime.Serialization.ISerializable or System.Xml.Serialization.IXmlSerializable interface.

• Support for change tracking is limited. To utilize the System.Data.DataTable class’s change tracking mechanism, the class that implements the column’s data type must either implement the System.ComponentModel.IChangeTracking interface, or take over the responsibility for informing the System.Data.DataRow when the column value has been modified, either by calling DataRow.SetModified on the row or by assigning the column value object to a separately instantiated column value object.