急!(在线等待)请帮我看一下我错在哪里啊

Question

class OleDbDataConnection
{
public int Initial(string sql)
{

MyConnection=new OleDbConnection(GetString());
MyConnection.Open();
//MyCommand=new OleDbCommand("select * from login where admin_name='"+txtadmin+"'and admin_password='"+txtpwd+"'",MyConnection);
            OleDbDataAdapter MyAdapter=new OleDbDataAdapter(sql,MyConnection);
DataSet MyDataSet=new DataSet();
MyAdapter.Fill(MyDataSet,"login");
    return MyDataSet.Tables["login"].Rows.Count.ToString();

         }
}
             class OleDbDataExecute
              {
                 private string txtadmin;
                 private string txtpwd;
                 public string GetSelect(string txtadmin,string txtpwd)
{
return "select * from login where admin_name='"+txtadmin+"'   and admin_password='"+txtpwd+"'"; }
public int SetSelect()
{  
   OleDbDataConnection DataConnection=new OleDbDataConnection();
                     return DataConnection.Initial(GetSelect(txtadmin,txtpwd));
}
              }
              class web
         {
              OleDbDataExecute MyExecute=new OleDbDataExecute();
              MyExecute.GetSelect(TextBox_admin.Text,TextBox_password.Text);
         }
我调试过程中发现段点放在GetSelect处GetSelect(),SetSelect()中的txtadmin,string txtpwd都会有TextBox_admin.Text,TextBox_password.Text的值,但是把断点放到SetSelect()上时我发现SetSelec()中的TextBox_admin.Text,TextBox_password.Text值为null,其中Initial(string sql)和GetSelect处GetSelect(),SetSelect()在不同的类中.请问这是什么回事啊

Answer 1

public int Initial(string sql)
{

MyConnection=new OleDbConnection(GetString());
MyConnection.Open();
//MyCommand=new OleDbCommand("select * from login where admin_name='"+txtadmin+"'and admin_password='"+txtpwd+"'",MyConnection);
            OleDbDataAdapter MyAdapter=new OleDbDataAdapter(sql,MyConnection);
DataSet MyDataSet=new DataSet();
MyAdapter.Fill(MyDataSet,"login");
    return MyDataSet.Tables["login"].Rows.Count.ToString();

         }你看清楚你的这个方法返回值是int型的
可是你方法中的return 返回的时string型的----return MyDataSet.Tables["login"].Rows.Count.ToString();
 方法定义的类型与方法中返回值语句不符合!
这样就会出错了

Answer 2

改成：public int Initial(string sql)
{

MyConnection=new OleDbConnection(GetString());
MyConnection.Open();
//MyCommand=new OleDbCommand("select * from login where admin_name='"+txtadmin+"'and admin_password='"+txtpwd+"'",MyConnection);
            OleDbDataAdapter MyAdapter=new OleDbDataAdapter(sql,MyConnection);
DataSet MyDataSet=new DataSet();
MyAdapter.Fill(MyDataSet,"login");
    return (int)MyDataSet.Tables["login"].Rows.Count;

         }

Answer 3

根断点是没有关系的 
只是那个你添加了断点  程序还没有运行到给txtadmin，txtpwd赋值 当然就是null了
没有仔细看你的代码 我想你的问题应该是这样的 但是有一点  断点放在那儿是不会影响程序执行效果的