C# ADO.NET SqlCommand - ExecuteReader

The ExecuteReader() in C# SqlCommand Object sends the SQL statements to the Connection Object and populate a SqlDataReader Object based on the SQL statement. When the ExecuteReader method in SqlCommand Object execute , it will instantiate a SqlClient.SqlDataReader Object.

The SqlDataReader Object is a stream-based , forward-only, read-only retrieval of query results from the Data Source, which do not update the data it contains. The SqlDataReader cannot be created directly from code, they can created only by calling the ExecuteReader method of a C# Command Object.

using System;
using System.Windows.Forms;
using System.Data.SqlClient; 

namespace WindowsApplication1
    public partial class Form1 : Form
        public Form1()

        private void button1_Click(object sender, EventArgs e)
            string connetionString = null;
            SqlConnection cnn  ;
            SqlCommand cmd ;
            string sql = null;
            SqlDataReader reader ;

            connetionString = "Data Source=ServerName;Initial Catalog=DatabaseName;User ID=UserName;Password=Password";
            sql = "Your SQL Statement Here , like Select * from product";

            cnn = new SqlConnection(connetionString);
                cmd = new SqlCommand(sql, cnn);
                reader = cmd.ExecuteReader();
                while (reader.Read())
                    MessageBox.Show(reader.GetValue(0) + " - " + reader.GetValue(1) + " - " + reader.GetValue(2));
            catch (Exception ex)
                MessageBox.Show("Can not open connection ! ");
} (C) 2021    Founded by raps mk
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