请大家看下我的代码哪来出错了？
在做一个系统，正在做登陆部分，因为经常要连接数据库，就自己写了个类
public class SQLcon
{
private string con = "server=(local);user id=sa;password=sa;database=student";
public SqlConnection ConnectToDatabase()
{
return new SqlConnection(con);
}
public bool Login(string uid, string pwd, SqlConnection mycon) //判断是否登陆成功
{
if (mycon.State != ConnectionState.Open)
{
MessageBox.Show("数据库未打开");
try
{
mycon.Open();
SqlCommand login = new SqlCommand();
string str = " select UserID from UserLogin where UserName='" + uid + "' and PassWord ='" + pwd + "' ";
login.CommandText = str;
login.Connection = mycon;
SqlDataReader result = login.ExecuteReader();
mycon.Close();
if (result.HasRows)
{
return true;
}
else
{
return false;
}
}
catch (Exception ex)
{
MessageBox.Show("数据库异常！请重试!");
return false;
}
}
else
{
MessageBox.Show("数据库已经打开");
mycon.Close();
return false;
}
}
}
private void LoginBotton_Click(object sender, EventArgs e)
{
bool login = false;
SQLcon conn = new SQLcon();
SqlConnection newCon = conn.ConnectToDatabase();
login = conn.Login(ID.Text.Trim(), Code.Text.Trim(),newCon);
if (login)
{
MainForm form1 = new MainForm();
form1.Show();
}
else
{
MessageBox.Show("登陆失败！");
}
}
login.CommandText = str;
login.Connection = mycon;
SqlDataReader result = login.ExecuteReader();
if (result.HasRows)
{
return true;
}
else
{
return false;
}
}
catch (Exception ex)
{
MessageBox.Show("数据库异常！请重试!");
return false;
}
finally
{ mycon.Close();}
