枚举与字符串转及RecordSet转XML，JSON

function AdoToJs(ado: TADOQuery): string;
var
  I, J: Integer;
  json: string;
begin
  json := '{columns:[';
  for I := 0 to ado.FieldCount - 1 do
  begin
    json := json + '{name:"' + ado.Fields[I].FieldName + '",type:"' + DbTypeToStr(ado.Fields[I].DataType) + '"}';
    if I < ado.FieldCount - 1 then
      json := json + ',';
  end;
  json := json + '],rows:[';
  for I := 0 to ado.RecordCount - 1 do
  begin
    json := json + '{';
    for J := 0 to ado.FieldCount - 1 do
    begin
      json := json + ado.Fields[J].FieldName + ':"' + ado.FieldByName(ado.Fields[J].FieldName).AsString + '"';
      if J < ado.FieldCount - 1 then
        json := json + ',';
    end;
    json := json + '}';
    if I < ado.RecordCount - 1 then
      json := json + ',';
  end;
  json := json + ']}';
  Result := json;
end;

function AdoToXml(ado: TADOQuery): string;
begin
  Result := RecordsetToXMLString(ado.Recordset);
end;

function XmlToAdo(xml: string): TADOQuery;
var
  ado: TADOQuery;
begin
  ado := TADOQuery.Create(nil);
  ado.Recordset := RecordsetFromXMLString(xml);
  Result := ado;
end;

function RecordsetToXMLString(const Recordset: ADOInt._Recordset): string;
var
  RS: Variant;
  Stream: TStringStream;
begin
  Result := '';
  if Recordset = nil then
    Exit;
  Stream := TStringStream.Create('', TEncoding.UTF8);
  try
    RS := CreateOleObject('ADODB.Recordset');
    RS := Recordset;
    RS.Save(TStreamAdapter.Create(Stream) as IUnknown, adPersistXML);
    Stream.Position := 0;
    Result := Stream.DataString;
  finally
    Stream.Free;
  end;
end;

function RecordsetFromXMLString(const xml: string): ADOInt._Recordset;
var
  RS: Variant;
  Stream: TStringStream;
begin
  Result := nil;
  if xml = '' then
    Exit;
  try
    Stream := TStringStream.Create(xml, TEncoding.UTF8);
    Stream.Position := 0;
    RS := CreateOleObject('ADODB.Recordset');
    RS.Open(TStreamAdapter.Create(Stream) as IUnknown);
    Result := IUnknown(RS) as ADOInt._Recordset;
  finally
    Stream.Free;
  end;
end;

function DbTypeToStr(dbtype: TFieldType): string;
begin
  Result := GetEnumName(TypeInfo(TFieldType), Ord(dbtype))
end;

function StrToDbType(const dbtype: string): TFieldType;
begin
  Result := TFieldType(GetEnumValue(TypeInfo(TFieldType), dbtype));
end;

http://www.cnblogs.com/toosuo/archive/2012/02/18/2357315.html