Using the <i class="emphasis">DataColumn</i> Class

Using the DataColumn Class

The DataColumn class represents a data column in a data table. Here is the inheritance hierarchy of this class:

Object
   MarshalByValueComponent
      DataColumn

You can find the more notable public properties of DataColumn objects in Table 22.33 and their more notable methods in Table 22.34. (This class has no non-inherited events.)

Table 22.33: Noteworthy public properties of *DataColumn* objects.
Property	Means
AllowDBNull	Gets/sets if null values are allowed.
AutoIncrement	Gets/sets if the column automatically increments the column's value when new rows are added to the table.
AutoIncrementSeed	Gets/sets the starting value for an autoincrement column.
AutoIncrementStep	Gets/sets the increment for an autoincrement column.
Caption	Gets/sets the caption for the column.
ColumnMapping	Gets/sets the column's mapping type.
ColumnName	Gets/sets the name of the column.
DataType	Gets/sets the type of data in the column.
DefaultValue	Gets/sets the default value for the column (used in new rows).
Expression	Gets/sets an expression used to filter rows, calculate the values, create aggregate values, and so on.
MaxLength	Gets/sets the maximum length of a text column.
Namespace	Gets/sets the XML namespace of the column.
Ordinal	Gets the position of the column in the Columns collection.
ReadOnly	Gets/sets if the column is read-only.
Table	Gets the table the column belongs to.
Unique	Gets/sets if the values in this column must be unique.

Table 22.34: Noteworthy public methods of *DataColumn* objects.
Method	Means
ToString	Gets the Expression value for this column, if there is one.