| Constraint | Represents a constraint that can be enforced on one or more DataColumn objects. |
| ConstraintCollection | Represents a collection of constraints for a DataTable. |
| ConstraintException | Represents the exception that is thrown when attempting an action that violates a constraint. |
| DBNull | Represents a nonexistent value. |
| DataColumn | Represents the schema of a column in a DataTable. |
| DataColumnCollection | Represents a collection of DataColumn objects for a DataTable. |
| DataException | Represents the exception that is thrown when errors are generated using ADO.NET components. |
| DataKey | Represents a DataKey created from not duplicated DataColumn |
| DataRelation | Represents a parent/child relationship between two DataTable objects. |
| DataRelationCollection | Represents the collection of DataRelation objects for this DataSet. |
| DataRow | Represents a row of data in a DataTable. |
| DataRowCollection | Represents a collection of rows for a DataTable. |
| DataRowState | Represents a state of rows. |
| DataRowView | Represents a customized view of a DataRow. |
| DataSet | Represents an in-memory cache of data. |
| DataTable | Represents one table of in-memory data. |
| DataTableCollection | Represents the collection of tables for the DataSet. |
| DataTableReader | The DataTableReader obtains the contents of one or more DataTable objects in the form of one or more read-only, forward-only result sets. |
| DataView | Represents a databindable, customized view of a DataTable for sorting, filtering, searching, editing, and navigation. |
| ForeignKeyConstraint | Represents an action restriction enforced on a set of columns in a primary key/foreign key relationship when a value or row is either deleted or updated. |
| InvalidConstraintException | Represents the exception that is thrown when incorrectly trying to create or access a relation. |
| MappingType | Specifies how a DataColumn is mapped. |
| UniqueConstraint | Represents a restriction on a set of columns in which all values must be unique. |