how could I filter out tickets which are closed in one sprint but their subtasks are not?

[Stefanie You]

Sometimes when I close one sprint, it will pop up warning like sprint cannot be closed because there're incomplete subtasks.
so I'd like to have a jira filter or some other tools could give me the tickets of this case, so that I could monitor if the case exists and remind team during the sprint. 

I tried some JQL query in jira filter, but don't work, so could some experts help me with that? thank you!

[Mirek]

Hi @Stefanie You 

I think you need to filter by sprint ID and sub-task issue type.. Something like this

sprint = <sprintID> and type = Sub-task

This should give you all sub-task in a given sprint. You can find ID of a spring by hovering your mouse over Sprint name in the parent ticket for example..

[Stefanie You]

thank you @Mirek ! 
I need to filter within jira tickets with sub-tasks, so how could this be translated in JQL?