mysql select query skipping first row values

Question

There is only a drop down list with student ID and a grid view with students' images in my web page. If I select a student Grid View has to show all the images of the selected student. Problem is when I select a student my grid view is skipping first two values. I mean if there are 6 images grid view shows only 4 images. Here is my code:

private void BindGrid()
{
    MySqlConnection con = new MySqlConnection(constr);
    MySqlCommand cmd = new MySqlCommand("SELECT * FROM images where Image_ID in (" + String.Join(",", getImage_ID()) + ")", con);
    MySqlDataAdapter da = new MySqlDataAdapter(cmd);
    DataTable dt = new DataTable();
    da.Fill(dt);
    gvImages.DataSource = dt;
    gvImages.DataBind();
}
private List<int> getImage_ID()
{
    List<int> i = new List<int>();
    MySqlConnection con = new MySqlConnection(constr);
    con.Open();
    string query = "Select Come_Image_ID1, Leave_Image_ID from register where Students_ID='" + getStudents_ID() + "' AND Come_Image_ID IS NOT NULL AND Leave_Image_ID IS NOT NULL"; 
    MySqlCommand cmd = new MySqlCommand(query);
    cmd.Connection = con;
    MySqlDataReader reader = cmd.ExecuteReader();
    while (reader.Read())
    {
        foreach (DbDataRecord s in reader)
        {
            i.Add(s.GetInt32(0));
            i.Add(s.GetInt32(1));
        }
    }
    reader.Close();
    return i;
}

What is the best coding practice for this issue?

Answer 1

You are mixing ways to read data. Either you a while loop:

while (reader.Read())
{
    i.Add(reader.GetInt32(0));
    i.Add(reader.GetInt32(1));
}

Or a foreach loop:

foreach (DbDataRecord s in reader)
{
    i.Add(s.GetInt32(0));
    i.Add(s.GetInt32(1));
}

But not both. Both the while and the foreach consume records from the cursor, and when you mix them like this you skip the records the while loop consumes.