What is the role of the SqlConnection object in ADO.NET?

Short answer: The SqlConnection object is responsible for opening a connection to a SQL Server database. It represents the physical connection to the data source and must be open before executing commands (like SqlCommand) or reading data (using SqlDataReader or SqlDataAdapter).

Example code

SqlConnection connection = new SqlConnection(connectionString); connection.Open(); // Execute database commands connection.Close();

Real-world example (ShopNest)

ShopNest opens a SqlConnection only for the query, then disposes it (using). Connection pooling reuses physical connections automatically.

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.