Introduction:
In this article,i am going to explain about what are the differences between dataset and datareader in asp.net sql
dataaccess.

Main:
As a DataReader, allowing forward-only access to the data
As a DataSet, allowing full control over the disconnected data

DataReader:–>

A DataReader is specific to a data provider (for example, SqlDataReader, OdbcDataReader, and OleDbDataReader).
The data retrieved through a DataReader is read-only.
The data retrieved through a DataReader is forward-only. Once the data has been cycled through, the DataReader must be closed and re-created in order to reaccess the data.
A DataReader presents data through a direct connection to the data source. Only one row of data is stored in memory at any one time.
A DataReader takes up few IIS and memory resources but annexes the database connection until it’s closed.
A DataReader lasts as long as the connection to the database is open. It can’t be persisted in a cookie or a session variable.
A DataReader has no concept of primary keys, constraints, views, or any other relational database management system concepts, except rows and columns.
A DataReader connects to only one data source.

DataSet:–>

The DataSet class isn’t a part of any data provider. It’s specific to .NET only. However, the DataAdapter used to fill the DataSet with Fill() is specific to a data provider (for example, SqlDataAdapter, OdbcDataAdapter, and OleDbDataAdapter).
The data retrieved through a DataSet is read-write.
You can work with data in a DataSet in any order you choose as many times as you like.
A DataSet stores all the data from the data source in memory at once.
A DataSet takes up a lot more IIS and memory resources to store all the data, but it doesn’t hold up a database connection until it’s closed. The connection needs to be open only when Fill() is called.
A DataSet lasts only until the page is reloaded (posted back), unless it’s somehow persisted (for example, in a session variable).
Columns in a DataReader are referenced by index or name.
You can reference columns in a DataSet by name, but you must also name the DataTable and identify the row (index) that contains the column.
A DataSet contains a collection of DataTable objects. A primary key may be set for each DataTable, and relationships and constraints may be established between them.
You can’t update a data source through a DataReader.
You can make changes to data in a DataSet, and then send those changes back to the data source.
A DataSet can be filled with Fill() from multiple data sources but, once the data is retrieved, is not connected to any of them.

Conclusion:
Hope this helps,
Happy coding.