Delete From Union

delete_from_union_example.sql

-- regular delete from union doesn't work
delete `METADATA_ENTRY`
from `METADATA_ENTRY`
where (`METADATA_ENTRY`.`WORKFLOW_EXECUTION_UUID` in
       ((select `WORKFLOW_EXECUTION_UUID` as x2
         from `WORKFLOW_METADATA_SUMMARY_ENTRY`
         where `ROOT_WORKFLOW_EXECUTION_UUID` = 'aaaa')
        union
        (select 'aaaa' as x2)))
  and (`METADATA_ENTRY`.`METADATA_KEY` like 'labels:%');

-- adding an extra (select * from ... as x99) works‽
delete `METADATA_ENTRY`
from `METADATA_ENTRY`
where (`METADATA_ENTRY`.`WORKFLOW_EXECUTION_UUID` in
       (select *
        from ((select `WORKFLOW_EXECUTION_UUID` as x2
               from `WORKFLOW_METADATA_SUMMARY_ENTRY`
               where `ROOT_WORKFLOW_EXECUTION_UUID` = 'aaaa')
              union
              (select 'aaaa' as x2)) as x99)
    )
  and (`METADATA_ENTRY`.`METADATA_KEY` like 'labels:%');