using System; using System.Data; using System.Data.SqlClient; class Program { static void Main(string[] args) { SqlConnection conn = new SqlConnection("Data Source=(local);Initial Catalog=TestDB;Integrated Security=True"); conn.Open(); SqlCommand cmd = new SqlCommand("SELECT * FROM Employees", conn); SqlDataReader reader = cmd.ExecuteReader(); DataTable dataTable = new DataTable(); dataTable.Load(reader); conn.Close(); } }In this example, we are using the SqlConnection and SqlCommand classes to retrieve data from a database. We are selecting all the data from a table called "Employees" and loading it into a DataTable using the ExecuteAsCollection method. Package library: System.Data.SqlClient