How to save the value of one variable to another variable in Oracle APEX?

I have two items in Oracle APEX and I want to make one item to have by default part of value of another item. I have tried by using SQL function TRIM:

SELECT TRIM('HH24:MI ' FROM TIME_AND_DATE) AS DATE FROM BILL;

TIME_AND_DATE - (format mask: DD-MM-YYYY HH24:MI)
DATE          - (format mask: DD-MM-YYYY)

But it returns an error.

Solution

If TIME_AND_DATE columns datatype is DATE and you want to put only date part of it into a variable, then TRUNC it (not TRIM).

SQL> select sysdate date_and_time,
  2         trunc(sysdate) truncated
  3  from dual;

DATE_AND_TIME       TRUNCATED
------------------- -------------------
15.05.2020 15:07:12 15.05.2020 00:00:00

SQL>

Next step is just the presentation; use TO_CHAR (or format mask in front end (Apex?)) to display it as you want, e.g.

SQL> select to_char(trunc(sysdate), 'dd-fmmonth-yyyy') result from dual;

RESULT
--------------------
15-svibanj-2020

SQL>