提示错误类EAccessViolation,进程中止。不知道怎么回事。。。

Question

procedure TTkwh.PageControl1Change(Sender: TObject);
begin
  Case PageControl1.ActivePageIndex of
    0:begin
        ADOQuery1.Close;
        ADOQuery1.SQL.Clear;
        ADOQuery1.SQL.Add('Select XuanZeTi.BH,Type.TypeName,XuanZeTi.TM,XuanZeTi.A,XuanZeTi.B,XuanZeTi.C,XuanZeTi.D,XuanZeTi.DA,XuanZeTi.CZ,NYD.NYD,XuanZeTi.TypeID,XuanZeTi.NY from XuanZeTi,Type,NYD where XuanZeTi.TypeID=Type.TypeID and XuanZeTi.NY=NYD.BH ORDER BY XuanZeTi.BH ASC');
        ADOQuery1.Open;
        XZ_DBGrid.Fields[0].DisplayLabel:='题号';
        XZ_DBGrid.Fields[1].DisplayLabel:='题型';
        XZ_DBGrid.Fields[2].DisplayLabel:='题目';
        XZ_DBGrid.Fields[3].DisplayLabel:='选项A';
        XZ_DBGrid.Fields[4].DisplayLabel:='选项B';
        XZ_DBGrid.Fields[5].DisplayLabel:='选项C';
        XZ_DBGrid.Fields[6].DisplayLabel:='选项d';
        XZ_DBGrid.Fields[7].DisplayLabel:='答案';
        XZ_DBGrid.Fields[8].DisplayLabel:='所在章节';
        XZ_DBGrid.Fields[9].DisplayLabel:='难易度';
        XZ_DBGrid.Fields[0].DisplayWidth:=5;
        XZ_DBGrid.Fields[1].DisplayWidth:=10;
        XZ_DBGrid.Fields[2].DisplayWidth:=20;
        XZ_DBGrid.Fields[3].DisplayWidth:=20;
        XZ_DBGrid.Fields[4].DisplayWidth:=20;
        XZ_DBGrid.Fields[5].DisplayWidth:=20;
        XZ_DBGrid.Fields[6].DisplayWidth:=20;
        XZ_DBGrid.Fields[7].DisplayWidth:=5;
        XZ_DBGrid.Fields[8].DisplayWidth:=10;
        XZ_DBGrid.Fields[9].DisplayWidth:=5;
      end;
    1:begin
        ADOQuery1.Close;
        ADOQuery1.SQL.Clear;
        ADOQuery1.SQL.Add('Select * from TianKong');
        ADOQuery1.Open;
        TK_DBGrid.Fields[0].DisplayLabel:='题号';
        TK_DBGrid.Fields[1].DisplayLabel:='题型';
        TK_DBGrid.Fields[2].DisplayLabel:='题目';
        TK_DBGrid.Fields[3].DisplayLabel:='空 1';
        TK_DBGrid.Fields[4].DisplayLabel:='空 2';
        TK_DBGrid.Fields[5].DisplayLabel:='空 3';
        TK_DBGrid.Fields[6].DisplayLabel:='空 4';
        TK_DBGrid.Fields[7].DisplayLabel:='空 5';
        TK_DBGrid.Fields[8].DisplayLabel:='应填空数';
        TK_DBGrid.Fields[9].DisplayLabel:='难易度';
        TK_DBGrid.Fields[10].DisplayLabel:='所在章节';
      end;
    2:begin
        ADOQuery1.Close;
        ADOQuery1.SQL.Clear;
        ADOQuery1.SQL.Add('Select * from JianDaTi');
        ADOQuery1.Open;
        JD_DBGrid.Fields[0].DisplayLabel:='题号';
        JD_DBGrid.Fields[1].DisplayLabel:='题型';
        JD_DBGrid.Fields[2].DisplayLabel:='题目';
        JD_DBGrid.Fields[3].DisplayLabel:='答案';
        JD_DBGrid.Fields[4].DisplayLabel:='难易';
        JD_DBGrid.Fields[5].DisplayLabel:='所在章节';
      end;
    3:begin
        ADOQuery1.Close;
        ADOQuery1.SQL.Clear;
        ADOQuery1.SQL.Add('Select * from YuanLiLunShu');
        ADOQuery1.Open;
        YLLS_DBGrid.Fields[0].DisplayLabel:='题号';
        YLLS_DBGrid.Fields[1].DisplayLabel:='题型';
        YLLS_DBGrid.Fields[2].DisplayLabel:='题目';
        YLLS_DBGrid.Fields[3].DisplayLabel:='答案';
        YLLS_DBGrid.Fields[4].DisplayLabel:='难易';
        YLLS_DBGrid.Fields[5].DisplayLabel:='所在章节';
      end;
    4:begin
        ADOQuery1.Close;
        ADOQuery1.SQL.Clear;
        ADOQuery1.SQL.Add('Select * from XiTongSheJi');
        ADOQuery1.Open;
        XTSJ_DBGrid.Fields[0].DisplayLabel:='题号';
        XTSJ_DBGrid.Fields[1].DisplayLabel:='题型';<<<<<<<<<<<<<<<<<<<<<<<<<<运行的时候箭头会指到这
        XTSJ_DBGrid.Fields[2].DisplayLabel:='题目';
        XTSJ_DBGrid.Fields[3].DisplayLabel:='答案';
        XTSJ_DBGrid.Fields[4].DisplayLabel:='难易';
        XTSJ_DBGrid.Fields[5].DisplayLabel:='所在章节';
      end;
    5:begin
        ADOQuery1.Close;
        ADOQuery1.SQL.Clear;
        ADOQuery1.SQL.Add('Select * from XiTongCZ');
        ADOQuery1.Open;
        XTCZ_DBGrid.Fields[0].DisplayLabel:='题号';
        XTCZ_DBGrid.Fields[1].DisplayLabel:='题型';
        XTCZ_DBGrid.Fields[2].DisplayLabel:='题目';
        XTCZ_DBGrid.Fields[3].DisplayLabel:='答案';
        XTCZ_DBGrid.Fields[4].DisplayLabel:='难易';
        XTCZ_DBGrid.Fields[5].DisplayLabel:='所在章节';
      end;
    6:begin
        ADOQuery1.Close;
        ADOQuery1.SQL.Clear;
        ADOQuery1.SQL.Add('Select * from ZhangJie');
        ADOQuery1.Open;
        ZJ_DBGrid.Fields[0].DisplayLabel:='序号';
        ZJ_DBGrid.Fields[1].DisplayLabel:='章节序号';
        ZJ_DBGrid.Fields[2].DisplayLabel:='章节名';
      end;
  end;
end;提示错误类EAccessViolation，错误信息：'Access violation at address 00481D5F in module'
TKSCXT.exe’.Read of address 00000038‘.进程中止.问题是不是出在上面的代码中呢?

Answer 1

红色属性说明可以关联其他的控件。有些是必须设置的，例如数据库敏感控件的datasource

Answer 2

红色属性说明可以关联其他的控件。有些是必须设置的，例如数据库敏感控件的datasource

Answer 3

所访问的内存已经被释放造成的，看你用到PageControl控件，检查下在切换页时是否释放了某些资源造成的。
出异常之后跟一下，看具体是哪行出的问题，这样才好查原因。

Answer 4

 恩，好的，确实是PageControl控件 这个地方的问题，在切换的时候就出错。

Answer 5

你可能加载了多余的DLL文件没有释放............

Answer 6

   谢谢各位了，就是DataSoure 没有设置好，给分咯。