C# interview questions :- In ADO.NET What is connection, command, datareader and dataset object ?

Answer:
Connection: - This object creates a connection to the database. If you want to do any operation on the database you have to first create a connection object.
Command: - This object helps us to execute SQL queries against database. Using command object we can execute select, insert, update and delete SQL command.
Data reader: - This provides a recordset which can be browsed only in forward direction. It can only be read but not updated. Data reader is goodfor large number of records where you want to just browse quickly and display it.
Dataset object: - This provides a recordset which can be read back and in forward direction. The recordset can also be updated. Dataset is like a in memory database with tables, rows and fields.
Data Adapter: - This object acts as a bridge between database and dataset; it helps to load the dataset object.
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.NET Interview Question - How does “Dataset” differ from a “Data Reader”?

.NET Interview Question - How does “Dataset” differ from a “Data Reader”?

• “Dataset” is a disconnected architecture, while “Data Reader” has live connection while reading data. If we want to cache data and pass to a different tier “Dataset” forms the best choice and it has decent XML support.

• When application needs to access data from more than one table “Dataset” forms the best choice.

• If we need to move back while reading records, “data reader” does not support this functionality.

• However, one of the biggest drawbacks of Dataset is speed. As “Dataset” carry considerable overhead because of relations, multiple table’s etc speed is slower than “Data Reader”. Use “Data Reader” when you want to quickly read and display records on a screen.


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