Pl sql date initialization comparsion ++ - oracle

Question

I have requirement where i have to get data of particular day. So my ideal startdate should be 2013-06-07 00:00:01 AM and end date 2013-06-07 23:59:59 AM
Hence i have written this code.
create or replace
PROCEDURE checkChanges
IS
vc_startDate timestamp;
vc_endDate timestamp;
begin
vc_startDate :=to_timestamp(TO_CHAR(trunc(systimestamp)-40+((24*60*60)-1)/(24*60*60),'yyyy-mm-dd hh24:mi:ss'),'yyyy-mm-dd hh24:mi:ss');
vc_endDate :=to_timestamp(TO_CHAR(trunc(systimestamp)+1/(24*60*60),'yyyy-mm-dd hh24:mi:ss'),'yyyy-mm-dd hh24:mi:ss');
Dbms_Output.Put_Line('vc_startDate ' ||vc_startDate);
Dbms_Output.Put_Line('vc_endDate ' ||vc_endDate);
SELECT EMAIL_ADRESS FROM SOMETABLE A,B
AND A.CREATE_TS BETWEEN vc_startDate AND vc_endDate ORDER BY B.START_DT;
end checkChanges;
But the start date and end date i am getting is quite different.
start date:07-JUN-13 12.00.01.000000 AM
end date: 07-JUN-13 11.59.59.000000 PM

Answer 1

Here's a simple way to do this.
DECLARE
v_start TIMESTAMP;
v_end TIMESTAMP;
BEGIN
v_start := TRUNC (SYSTIMESTAMP) + NUMTODSINTERVAL (1, 'second'); --truncate the timestamp and add one second
DBMS_OUTPUT.PUT_LINE (TO_CHAR (v_start, 'yyyy-mm-dd hh24:mi:ss'));
/*alternate way
v_start := TRUNC (SYSTIMESTAMP) + INTERVAL '0 0:0:1' DAY TO SECOND; --truncate the timestamp and add one second
DBMS_OUTPUT.PUT_LINE (TO_CHAR (v_start, 'yyyy-mm-dd hh24:mi:ss AM'));*/
v_end :=
TRUNC (SYSTIMESTAMP) --trunacate the timestamp
+ INTERVAL '1 0:0:0.0' DAY TO SECOND --add a day
- NUMTODSINTERVAL (1, 'second'); --substract a second
DBMS_OUTPUT.PUT_LINE (TO_CHAR (v_end, 'yyyy-mm-dd hh24:mi:ss'));
/*alternate way
v_end := TRUNC (SYSTIMESTAMP) --trunacate the timestamp
+ INTERVAL '0 23:59:59' DAY TO SECOND; --add hours, mins, s
DBMS_OUTPUT.PUT_LINE (TO_CHAR (v_end, 'yyyy-mm-dd hh24:mi:ss AM'));*/
EXCEPTION
WHEN OTHERS
THEN
DBMS_OUTPUT.PUT_LINE (SQLERRM);
END;
Output:
2013-06-07 00:00:01 AM
2013-06-07 23:59:59 PM
UPDATE
I also printed the values without converting to to_char and it displayed similar to what u got.
DBMS_OUTPUT.PUT_LINE (v_start);
DBMS_OUTPUT.PUT_LINE (v_end);
Output:
07-JUN-13 12.00.01.000000 AM
07-JUN-13 11.59.59.000000 PM
So, it seems what you are doing is correct(but, little complicated). When displaying the timestamp it is getting displayed according to the NLS parameters. Check that using
SELECT *
FROM nls_session_parameters
WHERE parameter = 'NLS_TIMESTAMP_FORMAT';
I guess it will return this DD-MON-RR HH.MI.SSXFF AM
Do not worry about how it is being displayed. A date/timestamp variable has no format. It matters only when you want to print it. If don't use to_char function, it'll take the format mask as defined in NLS parameters. If you want to override it, use to_char function and specify the mask.But when used in the query, it'll have the correct value.