关于Delphi的ODAC控件问题!急急急急急!!!

Question

我从外部倒入一个大型文本文件（字符数很多）Update到一个
Oracle数据库表中去，写入（Update）已成功,库表里字段的数据完整，但是我用Select查询出来再用FieldByName()方法读出来时数据就不完整了？哪位高手指导一下，谢谢！急急急急急!!!

Answer 1

是不是你的数据库字段中，允许的最大字符数不足啊？
不过大文本，建议使用Blob流字段来存储比较好，存取和读取都是用流相关的方法，应该不会有问题的

Answer 2

你用memo来显示你查询出来的字段值看看是不是完整.
对于大文本,如楼上所说的,最好用blob来读取.

Answer 3

使用CBlob来保存，然后使用TBlobField来读取

Answer 4

zzn007说得值得你去查一下. 不完整有可能是你字段大小不够啊.仔细查一下即可.

Answer 5

楼主，我现在也用odac，但是总提示我cannot modify a read-only dataset。
我是新手，不知道错在哪里！
请指教~！

Answer 6

楼上,看看是不是readonly设置成true.
或在修改的时候没有edit

Answer 7

谢谢以上的朋友，你们说的方法都试过了但还是不行,现将代码粘出，本代码本身就是要存入的文本
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, DB, MemDS, DBAccess, Ora, Provider, OraProvider, ADODB,
  Grids, DBGrids, DBCtrls;type
  TForm1 = class(TForm)
    OraProvider1: TOraProvider;
    OraSession: TOraSession;
    Query: TOraQuery;
    btnRead: TButton;
    Memo1: TMemo;
    btnWrite: TButton;
    Button3: TButton;
    Button4: TButton;
    quInsertRecord: TOraQuery;
    Button5: TButton;
    OpenDialog: TOpenDialog;
    Button6: TButton;
    DBGrid1: TDBGrid;
    DataSource1: TDataSource;
    OraQuery1: TOraQuery;
    BtnQuery: TButton;
    DBMemo1: TDBMemo;
    DataSource2: TDataSource;
    procedure Button3Click(Sender: TObject);
    procedure btnWriteClick(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure btnReadClick(Sender: TObject);
    procedure Button5Click(Sender: TObject);
    procedure Button6Click(Sender: TObject);
    procedure BtnQueryClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.Button3Click(Sender: TObject);
var
  f: TOpenDialog;
begin
  f := OpenDialog;
  f.Execute;
  memo1.Lines.LoadFromFile(f.FileName );
end;procedure TForm1.btnWriteClick(Sender: TObject);
var
  s: TStringStream;
  rData: WideString;
  f:TextFile;
  sSQL:String;
  //iSize:integer;
begin
  rData := memo1.Text;
  s := TStringStream.Create(Trim(rData));
  //iSize:=s.Size;
  //Application.MessageBox(PChar('s.size='+IntToStr(iSize)),'系统提示');
  try
    try
          with quInsertRecord do
          begin
            OptionsDS.LongStrings := True;
            Close;
            //SQL.Text := 'Update a set a1=EMPTY_CLOB() where a0=:a0 RETURNING a1 into :a1';
            SQL.Text := 'Update a set a1=:a1 where a0=:a0';
            Params.ParamByName('a0').AsString := '1';
            Params.ParamByName('a1').ParamType := ptInput;
            //Params.ParamByName('a1').DataType := ftOraClob;
            Params.ParamByName('a1').AsWideString:=s.DataString;
            //TBlobField(Params.ParamByName('a1')).SaveToFile('c:\直接输出.txt');
            AssignFile(f,'c:\aaa.txt');
            ReWrite(f);
            Write(f,Params.ParamByName('a1').AsWideString);
            Closefile(f);
            //Params.ParamByName('a1').AsOraClob.SaveToFile('c:\aaa.txt');
            //Application.MessageBox(PChar('s.size='+IntToStr(s.Size)),'写入');
            ExecSQL;
          end;
          showmessage('ok');
    except
       on e: exception do
          showmessage(e.Message);
    end;
  finally
      s.free;
  end;
end;procedure TForm1.Button4Click(Sender: TObject);
begin
  OraSession.Connected := True;
end;procedure TForm1.btnReadClick(Sender: TObject);
var
    s:TStringStream;
    iSize:Integer;
    sReadText:WideString;
    f:TextFile;
begin
      try
        with query do
        begin
          Close;
          SQL.Text := 'select a1 from a where a0=''1''';
          Open;
          if not Eof then
          begin
              //sReadText:=
              TBlobField(FieldByName('a1')).SaveToFile('c:\read.txt');
              //AssignFile(f,'c:\Read.txt');
              //ReWrite(f);
              //Write(f,sReadText);
              //Closefile(f);
             {s := TStringStream.Create(sReadText);
             iSize:=s.Size;
             Application.MessageBox(PChar('iSize='+IntToStr(iSize)),'系统提示');
             TBlobField(FieldByName('a1')).SaveToFile('c:\a1.txt');
             TBlobField(FieldByName('a1')).SaveToStream(s);
             Application.MessageBox(PChar('iSize='+IntToStr(iSize)),'系统提示');
             memo1.Lines.LoadFromStream(s);}
          end;
          Close;
        end;
      finally
         //s.Free;
      end;
end;procedure TForm1.Button5Click(Sender: TObject);
var
  Stream: TStream;
  BlobStream: TStream;
begin
  with quInsertRecord do
  begin
    SQL.Text := 'select * from a';
    Open;
    Edit;    Stream := nil;
    BlobStream := nil;
    try
      Stream := TFileStream.Create(OpenDialog.FileName, fmOpenRead);
      BlobStream := CreateBlobStream(
        FieldByName('Value'), bmWrite);      BlobStream.CopyFrom(Stream, 0);
    finally
      BlobStream.Free;
      Stream.Free;
    end;     post;
  end;
end;procedure TForm1.Button6Click(Sender: TObject);var
    s:TStringStream;
    BlobStream: TStream;
begin    BlobStream := nil;    try
      s := TStringStream.Create('');
      try
        with query do
        begin
          Close;
          SQL.Text := 'select a0 from rep_data where outter_field_fk=742 ';
          Open;
          if not Eof then
          begin             //TBlobField(FieldByName('a1')).SaveToFile('c:\1.txt');             BlobStream := CreateBlobStream(
                  FieldByName('a0'), bmRead);             s.CopyFrom(BlobStream,0);
          end;
          Close;
        end;
         memo1.text := s.DataString;
      finally
         s.Free;
         if assigned(BlobStream) then
         BlobStream.free;
      end;    except    end;
end;procedure TForm1.BtnQueryClick(Sender: TObject);
var
  sSQL:String;
begin
  sSQL:='select * from a';
  with self.OraQuery1 do
  begin
    Close;
    SQL.Clear;
    SQL.Append(sSQL);
    Open;
  end;
end;end.