//这窗口程序是一个登录界面。登录的用户存在Users 表里
但是当输入用户名和密码时都提示SqlDataReader myDataReader = myCommand.ExecuteReader();地方有错。
谁能帮我看下程序


public partial class LogForm : Form
    {
        MainForm mainForm;
        
        public LogForm(MainForm pFrom)
        {
            InitializeComponent();

            mainForm = pFrom;
            if (mainForm.myConnection.State == System.Data.ConnectionState.Closed)
            {
                MessageBox.Show("出错不能登录");
                this.Text = "登录数据库失败，请退出检查与数据库的连接";
                this.buttonNew.Enabled = false;
                this.buttonNew.Enabled = false;
            }


        }

        private void buttonLogon_Click(object sender, EventArgs e)
        {
            String commandstring = "SELECT * FORM Users";
            SqlCommand myCommand = new SqlCommand();
            myCommand.Connection = mainForm.myConnection;
             = commandstring;

            SqlDataReader myDataReader = myCommand.ExecuteReader();
           
            bool b_accepted = false;

            while(myDataReader.Read())
            {
                if(myDataReader.GetString(0).Trim() == textBox1.Text.Trim() && myDataReader.GetString(1).Trim() == textBox2.Text.Trim())
                {
                    b_accepted = true ;
                    break;
                }
            }

            if(b_accepted == false)
            {
                MessageBox.Show("输入有错，请重新输入");
            }
            else
            {
                mainForm.currentUser = this.textBox1.Text.Trim();
                this.Close();
            }
        }

        private void buttonQuit_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void buttonNew_Click(object sender, EventArgs e)
        {

        }
    }

怎么这么做  你的做法会不会太复杂了

建议：select * from users where name=@txtname and pwd=@pwd

如果有记录就说明登入成功了

恩恩，你的方法很简单
能告诉我的程序出错在哪儿吗？？

namespace 学生管理系统
{
    public partial class Form2 : Form
    {

        SqlDataAdapter adp;
        SqlConnection con;
      
        DataSet ds;
        public SqlConnection connet()
        {
            con = new SqlConnection();
            con.ConnectionString = "server=8E034699A78A421;database=学生成绩管理;uid=sa;pwd=sa";
            con.Open();
            return con;
        }
        public Form2()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                string str = "select * from 管理员 where 名称='" + textBox1.Text + "'";
                adp = new SqlDataAdapter(str, connet());
                ds=new DataSet();
                adp.Fill(ds, "admi");
                if (Convert.ToString(ds.Tables[0].Rows[0].ItemArray[1]) == textBox2.Text)
                {
                    MessageBox.Show("登录成功");
                  
                    Form1 f = new Form1();

                    f.ShowDialog();
                  
                }
                else
                {
                    MessageBox.Show("登录失败");
                }
            }
            catch (Exception ee)
            {
                MessageBox.Show(Convert.ToString(ee));
            }
            
        }

        private void button2_Click(object sender, EventArgs e)
        {
            textBox1.Text = "";
            textBox2.Text = "";
        }
    }
}
我是这么实现的

把你的错误信息贴上来,,,,,,我想可能是你实例化