原来使用ado来访问数据库，用在DataSnap中也很方便。后来便一直使用UniDac，可发现UniDac如果用在DataSnap中要比ado麻烦很多，尤其对自增长字段、缺省值的处理上，感觉对DataSnap支持不好(普通C/S应用还是非常好的)。
在Unidac官网上看到一个关于处理DataSnap中的AutoInc字段问题，记录在下面，我没有验证。
I use DataSnap delphi 2010.
UniQuery Component DMLRefresh Can fetch autoinc value,
but I cannot use it with datasnap.
I use Follow Code.
procedure TForm.dspDataAfterUpdateRecord(Sender: TObject; SourceDS: TDataSet; DeltaDS: TCustomClientDataSet; UpdateKind: TUpdateKind); begin if UpdateKind = ukInsert then quData.Fields[0].NewValue := GetLastID; end;
GetLastID function is fetch autoinc value.
the code works grate with DBExpress. But not UniDac.
Answer:
To solve this problem, it's needed to set the following options:
Code: Select all
TDataSetProvider.ResolveToDataSet := True;
TUniQuery.RequiredFields := False;
TUniQuery.SetFieldsReadOnly := False;In this case UniDAC will generate the SQL code, and the identity field value will be set automatically to the TUniQuery component. To update the identity field value in the TClientDataSet, component it's needed to use the following code:
Code: Select all
procedure TForm1.DataSetProvider1AfterUpdateRecord(Sender: TObject; SourceDS: TDataSet; DeltaDS: TCustomClientDataSet; UpdateKind: TUpdateKind);
begin
if UpdateKind = ukInsert then
DeltaDS.Fields[0].NewValue := UniQuery1.Fields[0].AsInteger;
end;