在delphi中三个形式：ADODB_TLB ADOInt ADODB

在delphi中三个形式：ADODB_TLB ADOInt ADODB
RecordSet在delphi中常见的转换问题

三个文件中都有，但都不同ADODB_TLB._RecordSet ADOInt._RecordSet ADODB.RecordSet

ADODataSet和ADOQuery只能接受ADOInt._RecordSet，不能接受ADODB_TLB._RecordSet

原生_RecordSet与ADOInt._RecordSet互转，应该可以实现，但我没有去研究。

【第一种应用】RecordSet与OleVariant互转，uses ADODB_TLB,不能用ro的binaryfromvariant，因为这是xml纯广本，不是olevariant 纯文本xml转olevariant会失真。需要用另行处理。

【第二种应用】RecordSet与Binary互转,uses uROTypes uROBinaryHelpers

【第三种应用】RecordSet与String互转,uses ADODB（delpih7自带的）

要点：

1.RecordSet转为String后，再由String变为OleVariant，转回RecordSet，会报错。

2.ADODataSet.RecordSet的值，可以用ADODB.RecordSet转来的RS，但不能用ADODB_TLB._RecordSet

【原生 ADO 与 Delphi ADOExpress 组件的对应关系】

1、Connection <=> ADOConnection.ConnectionObject;

2、Recordset <=> ADODataSet.Recordset;

3、Command <=> ADOCommand.CommandObject;

4、? <=> ADOQuery，因为 ADOQuery 根本就不是原生 ADO 对象

5、ExecSQL <=> ADODataSet.Open;

6、ExecSQLA <=> ADOCommand.Execute;

【第一种应用】RecordSet与OleVariant互转

function SetAdoStream(RDS : ADODB._RecordSet) : OleVariant;

var

Objstream : ADODB_TLB._Stream;

ObjRs1    : ADODB_TLB._RecordSet;

ObjRs2    : OleVariant;

begin

try

    Objstream:=CoStream.Create;

    ObjRs1:=ADODB_TLB.CoRecordset.Create;

    ObjRs2:=CreateOleObject('ADODB.RecordSet');

    ObjRs1:=ADODB_TLB._RecordSet(RDS);

    ObjRs1.Save(ObjStream,adPersistXML);

    ObjRs2.Open(ObjStream);

    Result:=ObjRs2;

    ObjRs1.Close;

    ObjRs1:=nil;

    ObjRs2:=NULL;

    ObjStream:=nil;

except

    Result:=NULL;

    ObjRs1.Close;

    ObjRs1:=nil;

    ObjRs2:=NULL;

    ObjStream:=nil;

end;

end;

function GetAdoStream(oStream : OleVariant) : ADODB._Recordset;

begin

Result:=IDispatch(oStream) As ADODB._RecordSet;

end;

  

【第二种应用】RecordSet与Binary互转

function RecordsetToTms(const Recordset: ADODB._Recordset; var Stream: Binary): boolean;

var

RS: OleVariant;

begin

Result := false;

if Recordset = nil then Exit;

Stream:=Binary.Create;

try

    RS := CreateOleObject('ADODB.Recordset');

    RS := Recordset;

    RS.Save(TStreamAdapter.Create(stream) as IUnknown, adPersistADTG);

    Stream.Position := 0;

    Result := true;

except

    on E:Exception do

    begin

      RS:=E.Message;

      Stream:=BinaryFromVariant(RS);

      Result:=False;

    end;

end;

end;

function RecordsetFromTms(Stream: Binary): ADODB._Recordset;

var

RS: OleVariant;

begin

Result := nil;

if Stream.Size < 1 then Exit;

try

Stream.Position := 0;

RS := CreateOleObject( 'ADODB.Recordset');

RS.Open(TStreamAdapter.Create(Stream) as IUnknown);

Result := IUnknown(RS) as ADODB._Recordset;

finally;

end;

end;

【第三种应用】RecordSet与String互转

function RecordsetToXMLString(const Recordset: adoint._Recordset): string;

var

RS: Variant;

Stream: TStringStream;

begin

Result :='';

if Recordset = nil then Exit;

Stream := TStringStream.Create('');

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);

    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;