Lesson I have learned:
If you need a REST API with any SQL statement, you can use either the Query Designer or Quick Report.
Example of using REST API with Quick Report:
https://MY_SERVER/main/ifsapplications/projection/v1/QuickReports.svc/QuickReport_xxxxxx(my_parameter='1234'))
Note: xxxxxx is a randomly generated number when we create a Quick Report.
Remember to use an underscore in QuickReport_xxxxxx.