oracle developer_ importing different forms of date in one column

I am trying to import the date columns with different types of date format. table name: fD column name: TRANS_DATE_TRANS_TIME this column has two forms of the date like below. date type1: 'MM/DD/YYYY HH24:MI' date type2: 'YYYY-MM-DD HH24:MI:SS' not surprisingly, SQL developer(oracle) cannot import this column as a DATE type. I aim to unify these forms as 'MM/DD/YYYY HH24:MI.' What I did was I import it as a VARCHAR2 type and try to write very complicate and difficult(?) query... and then I read someone wrote here that do not import date type data as a VARCHAR2 because of this. Then, is there any idea that I can import this column successfully? or I need to import it as a VARCHAR2 type and write down complicate query? (and I do not know this query either.. haha) this is what I did when I imported it as a VARCHAR2. ''' with DT as( select TRANS_DATE_TRANS_TIME from fD ) select TRANS_DATE_TRANS_TIME, replace(to_char(to_date(TRANS_DATE_TRANS_TIME, case when regexp_like(TRANS_DATE_TRANS_TIME,'[0-9]{1}/[0-9]{1}/[0-9]{4} [0-9]{1}:[0-9]{2}') then 'MM/DD/YYYY HH24:MI' when regexp_like(TRANS_DATE_TRANS_TIME,'[0-9]{2}/[0-9]{1}/[0-9]{4} [0-9]{1}:[0-9]{2}') then 'MM/DD/YYYY HH24:MI' when regexp_like(TRANS_DATE_TRANS_TIME,'[0-9]{1}/[0-9]{2}/[0-9]{4} [0-9]{1}:[0-9]{2}') then 'MM/DD/YYYY HH24:MI' when regexp_like(TRANS_DATE_TRANS_TIME,'[0-9]{1}/[0-9]{1}/[0-9]{4} [0-9]{2}:[0-9]{2}') then 'MM/DD/YYYY HH24:MI' when regexp_like(TRANS_DATE_TRANS_TIME,'[0-9]{2}/[0-9]{2}/[0-9]{4} [0-9]{1}:[0-9]{2}') then 'MM/DD/YYYY HH24:MI' when regexp_like(TRANS_DATE_TRANS_TIME,'[0-9]{1}/[0-9]{2}/[0-9]{4} [0-9]{2}:[0-9]{2}') then 'MM/DD/YYYY HH24:MI' when regexp_like(TRANS_DATE_TRANS_TIME,'[0-9]{2}/[0-9]{1}/[0-9]{4} [0-9]{2}:[0-9]{2}') then 'MM/DD/YYYY HH24:MI' when regexp_like(TRANS_DATE_TRANS_TIME,'[0-9]{2}/[0-9]{2}/[0-9]{4} [0-9]{2}:[0-9]{2}') then 'MM/DD/YYYY HH24:MI' when regexp_like(TRANS_DATE_TRANS_TIME,'[0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2}') then 'MM/DD/yyyy HH24:MI' end), 'MM/DD/yyyy HH24:MI'),'') as newT from DT; '''