Oracle Query to fetch data based on only time condition - sql

Question

I need to fetch the data for last six month based on when modified date but the records I need are having time greater than 1500H. Please assist.
I have tried below condition in my script but it's not working:
AND WHENMODIFIEDDATE >= to_date('2021-01-01 00:00:00', 'YYYY-MM-DD HH24:MI:SS')
AND WHENMODIFIEDDATE <= to_date('2021-06-01 23:59:59','YYYY-MM-DD HH24:MI:SS')
AND WHENMODIFIEDDATE >= to_date('15:00:00', 'HH24:MI:SS') ;
Data Type for column WHENMODIFIEDDATE: DATE
Sample Data:
AUDITORKEY AUDITORID AUDITORNAME STATUS WHENMODIFIEDDATE
9266165 xyz xyz A 2020-10-21 08:13:43.0

Answer 1

The phrase
AND WHENMODIFIEDDATE >= to_date('15:00:00', 'HH24:MI:SS')
does not look at hours. If you use the TO_DATE command on just a time component, we will automatically construct a FULL date, eg
SQL> alter session set nls_date_format = 'dd/mm/yyyy hh24:mi:ss';
Session altered.
SQL> select to_date('15:00:00', 'HH24:MI:SS') from dual;
TO_DATE('15:00:00',
-------------------
01/08/2021 15:00:00
This is why your third predicate is having no effect (or could easily have the wrong effect depending on your date criteria).
As others mentioned in the comments, if you want to get just the HOUR from a date, you can use options such as EXTRACT or TO_CHAR depending on the data type of the source column
SQL> create table t ( x timestamp , y date) ;
Table created.
SQL> insert into t values (localtimestamp, sysdate);
1 row created.
SQL> select extract(HOUR from x) from t;
EXTRACT(HOURFROMX)
------------------
11
SQL> select extract(HOUR from y) from t;
select extract(HOUR from y) from t
*
ERROR at line 1:
ORA-30076: invalid extract field for extract source
SQL> select to_number(to_char(y,'HH24')) from t;
TO_NUMBER(TO_CHAR(Y,'HH24'))
----------------------------
11