Hi Krum,
I have tried with following statement (you can add OH_DeleteFlag and OH_Client) and it worked at least on MSSQL but also should work on Oracle in the same way:
select OH_Name, OEA_EventType, OEA_TimePeriod from OH
inner join OEA on OEA_OH_Idnr = OH_IDNR
where OH_OTYPE = 'EVNT'
and OEA_EventType = 'TT'
and OEA_TimePeriod <'0015'