Chapter 8. DataColumns

The DataColumn defines the schema for a single column in a DataTable. The DataTable schema is defined by a collection of columns in the table along with any constraints. The DataColumn defines:

• The type of data that can be stored in the column

• The length of the column for text-based column types

• Whether the data in the column can be modified

• Whether the column values for each row must be unique

• Whether the column in rows can contain null values

• Whether the column values are automatically generated and the rules for generating those values

• Whether the column value is calculated based on an expression

As with all disconnected classes, the DataColumn is independent of the column in the underlying data source. As a result, its data type is defined as a .NET Framework data type that is matched to the data type in the data source.