CombBox is not populating the ValueMember Properly from MySQL in C#
private void cboMake_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (cboMake.SelectedIndex >= 0)
            cboModel.Enabled = true;
        else
            cboModel.Enabled = false;

        // get the foreign key value of the model id to get the make for each brand to populate here
        // MessageBox.Show(cboModel.ValueMember);
        // right now selectindex always shows -1.  why?
        // if it changes, you need to then enable the right cbo, else, disable.
        // but also, you need the mid, fk, so you can then do a new sql statement with the where clause to populate it.
        int fk = cboModel.SelectedIndex;
        string connStr = "server=123.456.7.8;user=root;database=car;port=3306; password=nowayjose";
        MySqlConnection conn = new MySqlConnection(connStr);
        try
        {
            string sql = "SELECT * FROM cs_model WHERE mid='fk'";
            MySqlCommand cmd = new MySqlCommand(sql, conn);
            DataTable dt = new DataTable();
            MySqlDataAdapter da = new MySqlDataAdapter(cmd);
            da.Fill(dt);
            cboMake.DataSource = dt;
            cboMake.DisplayMember = "model";
            cboMake.ValueMember = "mmid";
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString(), "MySQL Connection Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        conn.Close();
    }

    private void frmMain_Load(object sender, EventArgs e)
    {
        string connStr = "server=123.456.7.8;user=root;database=car;port=3306; password=nowayjose";
        MySqlConnection conn = new MySqlConnection(connStr);
        try
        {
            string sql = "SELECT * FROM cs_make";
            MySqlCommand cmd = new MySqlCommand(sql, conn);
            DataTable dt = new DataTable();
            MySqlDataAdapter da = new MySqlDataAdapter(cmd);
            da.Fill(dt);
            cboMake.DataSource = dt;
            cboMake.DisplayMember = "make";
            cboMake.ValueMember = "mid";
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString(), "MySQL Connection Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        conn.Close();
    }

private void cboMake_SelectedIndexChanged(object sender, EventArgs e)
    {

        int fk = cboModel.SelectedIndex;  // ?????
      .....
    }

string sql = "SELECT * FROM cs_model WHERE mid='fk'";

string sql = "SELECT * FROM cs_model WHERE mid=@mid";

MySqlCommand cmd = new MySqlCommand(sql, conn);
cmd.Parameters.AddWithValue("@mid", fk);

int fk = cboMake.SelectedValue;

private void cboMake_SelectedIndexChanged(object sender, EventArgs e) {
  if (cboMake.SelectedIndex == -1)
    cboModel.Enabled = false;
  else {
    cboModel.Enabled = true;
    int fk = cboMake.SelectedValue;

    using (var conn = new MySqlConnection(connStr))
    using (var cmd = new MySqlCommand("SELECT * FROM cs_model WHERE mid=@mid", conn))
    using (var da = new MySqlDataAdapter(cmd)) {
      cmd.Parameters.AddWithValue("@mid", fk);
      DataTable dt = new DataTable();
      da.Fill(dt);
      cboModel.DisplayMember = "model";
      cboModel.Validated = "mmid";
      cboModel.DataSource = dt;
    }
  }
}

private void cboMake_SelectedIndexChanged(object sender, EventArgs e)
    {


        int foreignKey = (int)cboMake.SelectedIndex +1;   // i forgot to cast the int from string since the database was tinyint, it still returns string in c#
        string fk = foreignKey.ToString();   // since i need the string for the query, back it goes, but i needed to do arithmetic
        string connStr = "server=10.18.30.1;user=notroot;database=car;port=3306;password=password";
        MySqlConnection conn = new MySqlConnection(connStr);
        try
        {
            string sql = "SELECT * FROM cs_model WHERE mid=" + fk;   // forgot to escape out of the string (used to php $var style within double quotes)
            MySqlCommand cmd = new MySqlCommand(sql, conn);
            DataTable dt = new DataTable();
            MySqlDataAdapter da = new MySqlDataAdapter(cmd);
            da.Fill(dt);
            cboModel.DataSource = dt;           // i had cboModel by a silly mistake
            cboModel.DisplayMember = "model";
            cboModel.ValueMember = "mmid";

        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString(), "MySQL Connection Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        conn.Close();
    }