I'm using public app query to get data via REST call from other place that public app uses internally.
It's an SQL query, so let's say I change query and deploy it as a draft release.
Now if I query via API, it gets live version of query. I want to also be able to test and get query of preview version.
Hello @Tornike_Kumelashvili,
You should be able to use the 'Revert to this version' button from the list of releases to view different versions of the same query and any changes that have been made to them, without needing to 'publish' the release or use the 'preview release' button.
After I click 'Revert to this version' I was able to see the results of a query change be applied to the table (I am switching back and forth between a query that has LIMIT 5 and the same query without limit) and I noticed that although the table changes the number of rows being displayed, I had to refresh the browser to see the query inspector change to reflect of having/losing the LIMIT 5 clause between the two recently published version of my app.
It seems that using 'Preview Release' will show the live app with the the LIMIT applied to the table, but then when I clicked on edit the table and query displayed the live version (without LIMIT) so that is something I can file a report to our engineers to improve. As it would make sense for a preview of the live app to allow for preview of the query's used in the app as well 
So for changing back and forth between two versions to test and compare, use 'Revert to this version' with a hard refresh. With 'Preview Release' just for viewing the live app to make sure it looks the way you want before you 'Publish Release' to make that version live to end users 
