Grid view not showing the first row ASP.NET , C# Sql server

Question

I am trying to show data from my SQL table on grid view, however, it is not showing the first row of data but the following rows of data a showing: Here is my code

public partial class DisplayGrid : System.Web.UI.Page
{
    string strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["PostbankConnectionString"].ConnectionString;
    string query = "SELECT * FROM tbl_user";

    protected void Page_Load(object sender, EventArgs e)
    {
        //query 
        SqlConnection con = new SqlConnection(strConnString);
        SqlCommand cmd = new SqlCommand(query, con);
        cmd.CommandType = CommandType.Text;

        SqlDataReader reader;
        con.Open();
        reader = cmd.ExecuteReader();


        if (reader.Read())
        {
            GridView1.DataSource = reader;
            //Bind the data
            GridView1.DataBind();
        }

        reader.Close();
        con.Close();
    }
}

Answer 1

Better to use DataTable and load contents of SqlDataReader with DataTable.Load() instead of assigning the reader contents directly to GridView instance:

DataTable dt = new DataTable();
using (SqlConnection con = new SqlConnection(strConnString))
{
    using (SqlCommand cmd = new SqlCommand(query, con))
    {
        cmd.CommandType = CommandType.Text;

        con.Open();
        SqlDataReader reader = cmd.ExecuteReader();

        if (reader.HasRows) // check if the reader contains rows
        {
            dt.Load(reader); // load to Datatable

            GridView1.DataSource = dt; // assign data source from DataTable
            GridView1.DataBind();
        }
    }
}

Note that SqlDataReader is forward-only stream , you need to use DataTable or other collections which able to perform both backward and forward lookups.

Answer 2

remove the line- if (reader.Read()) because DataReader.Read method advances the SqlDataReader to the next record.

Here is the code-

public partial class DisplayGrid : System.Web.UI.Page
{
    string strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["PostbankConnectionString"].ConnectionString;
    string query = "SELECT * FROM tbl_user";

    protected void Page_Load(object sender, EventArgs e)
    {
        //query 
        SqlConnection con = new SqlConnection(strConnString);
        SqlCommand cmd = new SqlCommand(query, con);
        cmd.CommandType = CommandType.Text;

        SqlDataReader reader;
        con.Open();
        reader = cmd.ExecuteReader();
           GridView1.DataSource = reader;
           //Bind the data
            GridView1.DataBind();
            reader.Close();
        con.Close();
    }
}