What is a Dataset?

Major component of ADO.NET is the DataSet object, which you can think of as being similar to an in-memory relational database. DataSet objects contain DataTable objects, relationships, and constraints, allowing them to replicate an entire data source, or selected parts of it, in a disconnected fashion.
A DataSet object is always disconnected from the source whose data it contains, and as a consequence it doesn't care where the data comes from�it can be used to manipulate data from a traditional database or an XML document, or anything in between. In order to connect a DataSet to a data source, you need to use a data adapter as an intermediary between the DataSet and the .NET data provider.


The dataset is a disconnected in-memory cache database. The dataset object model looks like this:
Dataset
DataTableCollection
DataTable
DataView
DataRowCollection
DataRow
DataColumnCollection
DataColumn
ChildRelations
ParentRelations
Constraints
PrimaryKey
DataRelationCollection
Let�s take a look at each of these:
DataTableCollection: As we say that a DataSet is an in-memory database. So it has this collection, which holds data from multiple tables in a single DataSet object.
DataTable: In the DataTableCollection, we have DataTable objects, which represents the individual tables of the dataset.
DataView: The way we have views in database, same way we can have DataViews. We can use these DataViews to do Sort, filter data.
DataRowCollection: Similar to DataTableCollection, to represent each row in each Table we have DataRowCollection.
DataRow: To represent each and every row of the DataRowCollection, we have DataRows.
DataColumnCollection: Similar to DataTableCollection, to represent each column in each Table we have DataColumnCollection.
DataColumn: To represent each and every Column of the DataColumnCollection, we have DataColumn.
PrimaryKey: Dataset defines Primary key for the table and the primary key validation will take place without going to the database.
Constraints: We can define various constraints on the Tables, and can use Dataset.Tables(0).enforceConstraints. This will execute all the constraints, whenever we enter data in DataTable.
DataRelationCollection: as we know that we can have more than 1 table in the dataset, we can also define relationship between these tables using this collection and maintain a parent-child relationship.