Code of hide tabpages

private void Login_Enter_but_Click(object sender, EventArgs e)
{
    this.m.connect.Open();
    this.mycmd = "select User_name , Password from Users where User_name='" + 
                 Login_YourName_txt.Text + 
                 "' and Password='" + login_pass_txt.Text + 
                 "'";
    this.command= new SqlCommand(this.mycmd,this.m.connect);
    if (this.command.ExecuteScalar() != null)
    {
        this.mycmd = "select U_State from Users where User_name='" + 
                     Login_YourName_txt.Text + 
                     "' and Password='" + 
                     login_pass_txt.Text + 
                     "'";
        this.command = new SqlCommand(this.mycmd, this.m.connect);
        string num = this.command.ExecuteScalar().ToString();
        if (num == "1")
        {
            this.Hide();
            Interfaces f = new Interfaces();
            f.Show();
            //f.tabControl1.TabPages.Remove(tabPage1);
            f.tabControl1.TabPages[0].Hide();
        }
        else
        {
            this.Hide();
            Interfaces f = new Interfaces();
            f.Show();
        }
        else
        {
            MessageBox.Show("Sorry,your name or passwrod are wrong try agian", "Sorry", 
                            MessageBoxButtons.OK, 
                            MessageBoxIcon.Warning);
            /* count++;
            if (count >= 4)
            {
                this.Close();
                count++;
            }*/
        }
        m.connect.Close();
    }
}