Hi, appleyuchi Sorry for the late reply, but could you describe you problem more or post your exception stack? The doc you posted has contained the section to define and register function. And I suggest you post your entire code in email directly that can reproduce the problem, thus the community can understand and help you resolve the question better.
Best， Leonard > > I'm learning document > <https://ci.apache.org/projects/flink/flink-docs-stable/dev/table/tableApi.html> > > part Flat Aggregate > > > My code is: > > https://paste.ubuntu.com/p/HmB4q2WJSb/ > > Could you tell me how to register TableAggregateFunction > > Thanks for your help
