Execute array values in query c#

Question

I'm busy with a task program and then I came on to a problem!

Here is my code:

int id = 1;
List<Button> _bListGroups = new List<Button>();
MySqlCommand mcCommandUserID = new MySqlCommand("SELECT * FROM pakket WHERE gebruikersid=@id", _msConnection);
mcCommandUserID.Parameters.AddWithValue("@id", id);
MySqlDataReader msReader = mcCommandUserID.ExecuteReader();
DataTable dtGetUserid = new DataTable();
dtGetUserid.Load(msReader);

string[] nummer = new string[10];

int i = 0;
foreach (DataRow row in dtGetUserid.Rows)
{
    nummer[i] = row["groepsid"].ToString();
    i++;
}

MySqlCommand msCommandGetGroup = new MySqlCommand("SELECT * FROM groep WHERE id=@id",_msConnection);
msCommandGetGroup.Parameters.AddWithValue("@id", nummer[i]);
MySqlDataReader msGetGroup = msCommandGetGroup.ExecuteReader();
DataTable dtGetGroup = new DataTable();
dtGetGroup.Load(msGetGroup);

int mtop = 10;
int mleft = 15;
int count = 1;
foreach (DataRow dr in dtGetGroup.Rows)
{
    Button temp = new Button();
    temp.Name = "bt" + dr["id"];
    temp.Text = (string)dr["groepsnaam"];
    temp.Width = 125;
    temp.Height = 125;
    temp.Left = mleft;
    temp.Top = mtop;

    mleft += 127;

    if (count == 2)
    {
        mtop += 125;
        mleft = 15;
        count = 0;
    }
    count++;
    _bListGroups.Add(temp);

}
return _bListGroups.ToArray();

When i give my array a specific number(like nummer[1]) i get one button back but if I use the variable i, it doesn't give me any buttons. I already tried to debug it but I couldn't solve it.

Answer 1

Note that you are increasing i in the end of every iteration. So in the end i is greater than the last assigned index by 1. Therefore you need i-1:

msCommandGetGroup.Parameters.AddWithValue("@id", nummer[i-1]);

Also you might want to have some prechecks here for edge cases, say when there is no rows in dtGetUserid.Rows.

Answer 2

You've failed to reset your counter.

the variable i is at this stage:

  msCommandGetGroup.Parameters.AddWithValue("@id", nummer[i]);

set to an array index which you havent allocated with any values.