Question

这是我的C＃代码：

public ReportForm(string type,string param1,string param2,string param3,string param4,string param5)
{
    cn.ConnectionString = @"Data Source=.\SQLExpressAttachDbFilename=|DataDirectory|Tourism.mdf;Persist Security Info=True;User ID=sa;Password=xxxxxxx";
    cn.Open();
    cm.Connection = cn;
    if (type == "OmraGroup")
    {
        string sql = "SELECT * from Clients where OmraGroupID='" + param1 + "'";
        DataSet1 ds = new DataSet1();
        SqlDataAdapter sda = new SqlDataAdapter(sql, cn);
        sda.Fill(ds.Tables["Clients"]);
        OmraReport v = new OmraReport();
        v.SetDataSource(ds.Tables["Clients"]);
        crystalReportViewer1.ReportSource = v;
        crystalReportViewer1.Refresh();
    }
}

它在前一行之前的行中给出了异常object reference not set to an instance of an object。它和我一样多年来一直很有魅力，当我再次使用那段代码时，它突然给了我这个例外。出了什么问题？

这里是堆栈跟踪

TourismCo.exe！TourismCo.Reporting.ReportForm.ReportForm（string type，string param1，string param2，string param3，string param4，string param5）Line 34 C＃       TourismCo.exe！TourismCo.FrontEnd.Religional.Omra.button10_Click（object sender，System.EventArgs e）第151行+ 0x124字节C＃       System.Windows.Forms.dll！System.Windows.Forms.Control.OnClick（System.EventArgs e）+ 0x65 bytes
      System.Windows.Forms.dll！System.Windows.Forms.Button.OnMouseUp（System.Windows.Forms.MouseEventArgs mevent）+ 0x113 bytes
      System.Windows.Forms.dll！System.Windows.Forms.Control.WmMouseUp（ref System.Windows.Forms.Message m，System.Windows.Forms.MouseButtons button，int clicks）+ 0x3e7 bytes       System.Windows.Forms.dll！System.Windows.Forms.Control.WndProc（ref System.Windows.Forms.Message m）+ 0xd39 bytes       System.Windows.Forms.dll！System.Windows.Forms.ButtonBase.WndProc（ref System.Windows.Forms.Message m）+ 0x1da bytes
      System.Windows.Forms.dll！System.Windows.Forms.Button.WndProc（ref System.Windows.Forms.Message m）+ 0x24 bytes
      System.Windows.Forms.dll！System.Windows.Forms.Control.ControlNativeWindow.WndProc（ref System.Windows.Forms.Message m）+ 0x46 bytes
      System.Windows.Forms.dll！System.Windows.Forms.NativeWindow.DebuggableCallback（System.IntPtr hWnd，int msg，System.IntPtr wparam，System.IntPtr lparam）+ 0xad bytes       [原产于管理过渡]
      [管理到原生过渡]
      System.Windows.Forms.dll！System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop（int dwComponentID，int reason，int pvLoopData）+ 0x5c3 bytes
      System.Windows.Forms.dll！System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner（int reason，System.Windows.Forms.ApplicationContext context）+ 0x578 bytes
      System.Windows.Forms.dll！System.Windows.Forms.Application.ThreadContext.RunMessageLoop（int reason，System.Windows.Forms.ApplicationContext context）+ 0x65 bytes
      TourismCo.exe！TourismCo.Program.Main（）第17行+ 0x28字节C＃       [原产于管理过渡]
      [管理到原生过渡]
      Microsoft.VisualStudio.HostingProcess.Utilities.dll！Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly（）+ 0x47 bytes
      mscorlib.dll！System.Threading.ExecutionContext.Run（System.Threading.ExecutionContext executionContext，System.Threading.ContextCallback callback，object state）+ 0x9b bytes
      mscorlib.dll！System.Threading.ThreadHelper.ThreadStart（）+ 0x4d bytes

对象引用未设置为对象的实例C＃使用Crystal Report

0 个答案: