ADO.NET

ExecuteScalar method is used to execute SQL Commands or storeprocedure, after executing return a single value from the database. It returns the first column of the first row in the result set from a database. 

SqlDataAdadpter

try

            {

                string ConString = "data source=.; database=StudentDB; integrated security=SSPI";

                using (SqlConnection connection = new SqlConnection(ConString))

                {

                    SqlDataAdapter da = new SqlDataAdapter("select * from student", connection);

                   

                    //Using Data Table

                    DataTable dt = new DataTable();

                    da.Fill(dt);

                    Console.WriteLine("Using Data Table");

                    foreach (DataRow row in dt.Rows)

                    {

                        Console.WriteLine(row["Name"] +",  " + row["Email"] + ",  " + row["Mobile"]);

                    }

                    Console.WriteLine("---------------");

                    //Using DataSet

                    DataSet ds = new DataSet();

                    da.Fill(ds, "student");                  

                    Console.WriteLine("Using Data Set");

                    foreach (DataRow row in ds.Tables["student"].Rows)

                    {

                        Console.WriteLine(row["Name"] + ",  " + row["Email"] + ",  " + row["Mobile"]);

                    }                    

                }

            }

            catch (Exception e)

            {

                Console.WriteLine("OOPs, something went wrong.\n" + e);

            }

            Console.ReadKey();