C# 和 Oracle，登录表单 : Operation is not valid due to the current state of the object

Question

  private void bLogIn(object sender, EventArgs e)
    {

        string logging = "select * from CLIENT where LOGIN='" + this.t_Login.Text + "' and PASSWORD='" + this.t_Password.Text + "' ;";

        OracleConnection conn = new OracleConnection("Data Source=XXX/orcl;User Id=XXX;Password=XXX;");
        OracleCommand cmd = new OracleCommand();

        cmd.CommandText = logging;
        cmd.Connection = conn;
        try
        {
            conn.Open();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }



        int count = 0;

        OracleDataReader reader = cmd.ExecuteReader();  // At this line there is the error: Operation is not valid due to the current state of the object

        while (reader.Read())
        {
           count = count + 1;
        }
        if (count == 1)
        {
        MessageBox.Show("Welcome");
        }
        else
        {
            MessageBox.Show("Wrong Password");
        }
        conn.Dispose();
    }

这是适用于 MySQL 的代码，但在转换为 Oracle 后就无法使用了。我究竟做错了什么？哪里不一样了。应该和 MySQL 一样简单吧？

为什么“OracleDataReader reader = cmd.ExecuteReader();”导致错误:“由于对象的当前状态，操作无效”???

Answer 1

您没有将连接分配给 cmd.. 尝试下面的代码

OracleCommand cmd = new OracleCommand();
cmd.connection = conn;
cmd.CommandText = logging;
int count = 0;
OracleDataReader reader = cmd.ExecuteReader();