Use Case:?

Short answer: DataReader is ideal when you only need to read the data sequentially and don’t need to modify the data or navigate backward.

Explain a bit more

DataSet is better when you need to work with disconnected data, modify it offline, and later update the database. Example (using DataReader for better performance): SqlCommand command = new SqlCommand("SELECT * FROM Customers", connection); connection.Open(); SqlDataReader reader = command.ExecuteReader(); while (reader.Read()) { Console.WriteLine(reader["CustomerName"].ToString()); } reader.Close(); When to Use: Use DataReader for large result sets where you need fast, sequential data access without requiring complex data manipulation. Use DataSet when you need to work with a disconnected data model or need to modify data offline.

Real-world example (ShopNest)

ShopNest’s reporting job still uses ADO.NET for a heavy SQL query where raw performance and stored procedures matter more than EF convenience.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.