How to display time only - oracle

Question

Can anyone help me how can I change the output of Time_done to a time only (example: 5:00AM)? If I add TO_CHAR(SYSDATE, 'HH24:MI:SS') on SYSDATE, I got an error message
ORA-01843: not a valid month.
Below are my codes and screen capture of EVENTLOGS table
CREATE TABLE EVENTLOGS(
Eventlog_id Number(3,0) NOT NULL,
User_name Varchar2(20),
Date_done Date,
Time_done Timestamp,
Action_done Varchar2(50),
CONSTRAINT PK_EVENTLOGS PRIMARY KEY (Eventlog_id));
/* TRIGGER CREATION */
CREATE OR REPLACE TRIGGER SUPERHEROES_AUDIT
AFTER INSERT OR DELETE OR UPDATE ON SUPERHEROES
FOR EACH ROW
ENABLE
DECLARE
V_LOGID NUMBER;
V_USER VARCHAR(30);
V_DATE DATE;
BEGIN
SELECT EVENTLOG_ID_SEQ.NEXTVAL, USER INTO V_LOGID, V_USER FROM DUAL;
IF INSERTING THEN
INSERT INTO EVENTLOGS(Eventlog_id, User_name, Date_done, Time_done, Action_done)
VALUES (V_LOGID, V_USER, SYSDATE, SYSDATE, 'INSERT');
ELSIF DELETING THEN
INSERT INTO EVENTLOGS(Eventlog_id, User_name, Date_done, Action_done)
VALUES (V_LOGID, V_USER, V_DATE, SYSDATE, SYSDATE, 'DELETE');
ELSIF UPDATING THEN
INSERT INTO EVENTLOGS(Eventlog_id, User_name, Date_done, Action_done)
VALUES (V_LOGID, V_USER, V_DATE, SYSDATE, SYSDATE, 'UPDATE');
END IF;
END;
/
[![INSERT INTO
EMPLOYEE_T (EmployeeID, EmployeeName, EmployeeAddress, EmployeeCity, EmployeeState, EmployeeZip, EmployeeBirthDate, EmployeeDateHired, EmployeeSupervisor)
VALUES (2, 'JACKIE', 'AFRICA', 'kenya', 'NO', 11285, TO_DATE('13-OCT-1950', 'DD-MM-YYYY'), TO_DATE('27-JUN-2014', 'DD-MM-YYYY'), 455789);][1]][1]

Answer 1

You have posted an incomplete TRIGGER code with too many errors.
If you are inserting data into a TIMESTAMP column, you need to insert a compatible record. Inserting only time portion is not useful as you cannot do direct date arithmetic / comparison operations which may be required on the column. I have used SYSTIMESTAMP function here to insert current system TIMESTAMP
CREATE OR REPLACE TRIGGER SUPERHEROES_AUDIT
AFTER INSERT OR DELETE OR UPDATE ON SUPERHEROES
FOR EACH ROW
ENABLE
DECLARE
V_LOGID NUMBER;
V_USER VARCHAR(30);
V_DATE DATE;
BEGIN
SELECT EVENTLOG_ID_SEQ.NEXTVAL, USER, SYSDATE INTO V_LOGID, V_USER, V_DATE FROM DUAL;
IF INSERTING THEN
INSERT INTO EVENTLOGS(Eventlog_id, User_name, Date_done, Time_done,Action_done)
VALUES (V_LOGID, V_USER, V_DATE, SYSTIMESTAMP, 'INSERT');
ELSIF DELETING THEN
INSERT INTO EVENTLOGS(Eventlog_id, User_name, Date_done,Time_done, Action_done)
VALUES (V_LOGID, V_USER, V_DATE, SYSTIMESTAMP, 'DELETE');
ELSIF UPDATING THEN
INSERT INTO EVENTLOGS(Eventlog_id, User_name, Date_done,Time_done, Action_done)
VALUES (V_LOGID, V_USER, V_DATE, SYSTIMESTAMP, 'UPDATE');
END IF;
END;
/
Here is the sample data
select * FROM EVENTLOGS;
EVENTLOG_ID USER_NAME DATE_DONE TIME_DONE ACTION_DONE
----------- -------------- --------- ------------------------------- ------------
1 SLDDEVELOPER 13-OCT-17 13-OCT-17 04.58.07.237343000 AM INSERT
If you need only time portion and not the DATE portion in your time_done column, then it should be a VARCHAR2 column and you can use TO_CHAR while inserting in this case as you were attempting to do.
INSERT INTO EVENTLOGS(Eventlog_id, User_name, Date_done, Time_done,Action_done)
VALUES (V_LOGID, V_USER, V_DATE, TO_CHAR(SYSDATE,'HH24:MI:SS'), 'INSERT');