How to create day start and end date in PL SQL - sql

Question

What I am trying to do is to create two timestamps a StartDate timestamp which will be 09/08/2015 00:00:00 and an EndDate time stamp which should be 09/08/2015 23:59:59 as easy as it is to achieve in MS SQL, I have not been able to find a Make_Date function or Add_Days function to get either of the timestamps in Oracle PL SQL.
Can anyone help me out?

Answer 1

Rather than using fractional numbers 86399 / 86400 (which requires some working out when reviewing the code to see why you picked those magic numbers) to get the end date you can explicitly state the time periods using INTERVALS (which is easy to see at a glance what you are doing):
SQL Fiddle
Oracle 11g R2 Schema Setup:
Query 1:
SELECT TRUNC( CURRENT_DATE ) AS START_DATE,
TRUNC( CURRENT_DATE ) + INTERVAL '1' DAY - INTERVAL '1' SECOND AS END_DATE
FROM DUAL
Results:
| START_DATE | END_DATE |
|-----------------------------|-----------------------------|
| September, 08 2015 00:00:00 | September, 08 2015 23:59:59 |

Answer 2

Use TO_DATE to convert string into DATE.
SQL> alter session set nls_date_format='mm/dd/yyyy hh24:mi:ss';
Session altered.
SQL> SELECT to_date('09/08/2015 00:00:00' ,'mm/dd/yyyy hh24:mi:ss') start_date,
2 to_date('09/08/2015 23:59:59' ,'mm/dd/yyyy hh24:mi:ss') end_date
3 FROM dual;
START_DATE END_DATE
------------------- -------------------
09/08/2015 00:00:00 09/08/2015 23:59:59
SQL>
You could also use the ANSI TIMESTAMP Literal.
SQL> SELECT TIMESTAMP '2015-08-09 00:00:00' start_date,
2 TIMESTAMP '2015-08-09 23:59:59' end_date
3 FROM dual;
START_DATE END_DATE
---------------------------- -------------------------------
09-AUG-15 12.00.00.000000000 09-AUG-15 11.59.59.000000000 PM
SQL>
Update OP wants the date literal to be dynamic.
SQL> SELECT TRUNC(SYSDATE) start_date,
2 TRUNC(SYSDATE) + 86399 / 86400 end_date
3 FROM dual;
START_DATE END_DATE
------------------- -------------------
09/08/2015 00:00:00 09/08/2015 23:59:59
Update 2 OP wants to know why the time part is hidden in the date.
SQL> alter session set nls_date_format='mm/dd/yyyy';
Session altered.
SQL> SELECT sysdate FROM DUAL;
SYSDATE
----------
09/08/2015
SQL> alter session set nls_date_format='mm/dd/yyyy hh24:mi:ss';
Session altered.
SQL> SELECT sysdate FROM DUAL;
SYSDATE
-------------------
09/08/2015 15:46:14
So, what happened above? The same SYSDATE returns two different values. The reason is that the DATE has both datetime elements, what you see depends on the display properties driven by your locale-specific NLS settings.
Use TO_CHAR to convert the date into string to display it in your
desired format.

Answer 3

Using values from table:
SELECT
DATE_VALUE,
TRUNC(DATE_VALUE) START_DATE,
TRUNC(DATE_VALUE) + 86399 / 86400 END_DATE
FROM
(SELECT SYSDATE - LEVEL + 1 DATE_VALUE FROM DUAL CONNECT BY LEVEL <= 10)