DataSnap——利用TParams进行多表事务更新

来源：互联网发布：淘宝买摩托车编辑：程序博客网时间：2024/05/20 11:24

服务端：

function TSVRDM.multUpdatesByPar(UpdateParam: TParams; out ErrMsg: string): OleVariant;const  aSQL = 'Select * from %s where 1<>1';var  i: Integer;  lQuery: TADOQuery;  lProvider: TDataSetProvider;  conn: TADOConnection;  ErrorCount, MaxErrors: Integer;begin  Writeln(fguid + '：Mult-Table Update start ...');  conn := ConnPool.Lock(dbConnStr);  lQuery := TADOQuery.Create(nil);  lProvider := TDataSetProvider.Create(nil);  Writeln(fguid + ': Start Transaction... ');  conn.BeginTrans;  try    try      lQuery.Connection := conn;      lProvider.DataSet := lQuery;      for I := 0 to UpdateParam.Count - 1 do begin        Writeln(fguid + ': Update Table ' + UpdateParam[i].Name);        lQuery.Close;        lQuery.SQL.Clear;        lQuery.SQL.Text := Format(aSQL, [UpdateParam[i].Name]);        result := lProvider.ApplyUpdates(UpdateParam[i].AsBytes, 0, ErrorCount);        ErrMsg := FErrMsg;        if ErrorCount > 0 then          raise Exception.Create(ErrMsg + '; TableName = ' + UpdateParam[i].Name);      end;      conn.CommitTrans;      Writeln(fguid + ': Transaction commited... Update finished！');    except      on E: Exception do      begin        conn.RollbackTrans;        Writeln(fguid + '：Transaction rollbacked! Update ERROR :' + E.Message);      end;    end;  finally    lProvider.Free;    lQuery.Free;    ConnPool.Unlock(conn);    FErrMsg := '';  end;end;

客户端：

procedure TMyClient.btn1Click(Sender: TObject);var  aParams: TParams;  aPar: TParam;  client: TDMClient;  ErrMsg: string;begin// TClientDataSet的Data和Delta可用TParam.AsBytes直接传递  aParams := TParams.Create(nil);  if ClientDataSet1.ChangeCount > 0 then  begin    aPar := aParams.CreateParam(ftVarBytes, '订单表', ptInput);//有可能是主表    aPar.AsBytes := ClientDataSet1.Delta;  end;  if ClientDataSet2.ChangeCount > 0 then  begin    aPar := aParams.CreateParam(ftVarBytes, '订单明细表', ptInput);//有可能是从表    aPar.AsBytes := ClientDataSet2.Delta;  end;  if aParams.Count = 0 then    exit;  client := TDMClient.Create(self.SQLConn.DBXConnection);  try    try      client.multUpdatesByPar(aParams, ErrMsg);      if ErrMsg <> '' then        raise Exception.Create(ErrMsg)      else      begin        ClientDataSet1.MergeChangeLog;        ClientDataSet2.MergeChangeLog;      end;    except      on E: Exception do      begin        showmessage(E.Message);      end;    end;  finally    client.Free;  end;end;

转自：http://www.cnblogs.com/hnxxcxg/p/6897116.html

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