SQLインジェクション(SQL Injection)の攻撃方法を学ぶ

private void Login()
{
string uname = tbName.Text;
string pwd = tbPassword.Text;
string sqlCmd = "select * from [Users] where UserName = '" + uname + "'";
string sqlCmdRep = sqlCmd.Replace("Users", "XXX").Replace("UserName", "XXX");
lbSQL.Text = sqlCmdRep;
try


DataTable dt = DataSQLServer.GetDataTable(sqlCmd);
gvResult.DataSource = dt;
gvResult.DataBind();
If (dt.Rows.Count == 1 && pwd == dt.Rows[0]["Password"].ToString())
{
lbRes.Text = dt.Rows[0]["UserName"] + " Login Success!";
}
else if(dt.Rows.Count == 0)
{
lbRes.Text = uname + " not exist!";
}
else
{
lbRes.Text = "Login Fail!";
}
}
catch (Exception ex)
{
lbRes.Text = "Error: " + ex.Message;
}
}