What are the differences between Dataset and DataReader

Dataset is in memory representation of the Database. where 

you can create tables, relations between tables, add 

primary key to tables and also manipulate the data 

retrieved form the database. It allows us to work in 

connection less environment.

Datareader is like forward only readonly cursor, which is 

used to retrieve data. data manipulation is not possible 

while using datareader. datareader continously keeps the 

connection open.

A ds (dataset) can be used when the connection is closed.

A dr (datareader) needs the connection open to be used.

A ds can be used to modify or delete or insert data in the 

database. 

A data reader can be used only to read data

A ds can let you access the info on any order at any time.

A dr lets you access the info only one time per item and 

only in a sequential order.

A ds data can be loaded in longer time than a dr can be 

loaded at.

A ds can contain separated and structured data from several 

database tables. 

A dr can contain data in one register per item, that 

register can include data from serveral tables id the sql 

select statement so indicates, but it has no separate 

structure per table.