PLSQL - Round Date to the nearest century? - sql

Question

Here is the output I am trying to get:
Number of slashes: 2
In 25 days it is: 19-FEB-15
The raw number is:
1.666666667E-01
The rounded number is: .17
Nearest Century: 01-JAN-01
I'm really not sure how to round "dDate25" to the nearest century?
Here is the code I have so far:
SET SERVEROUTPUT ON
DECLARE
vFilePath VARCHAR2 (100) := 'c\Temp\ProcDB.mdf';
vFilePath1 VARCHAR2 (100);
nNumber16 FLOAT;
dDate25 DATE := SYSDATE+25;
BEGIN
vFilePath1 := REPLACE (vFILEPATH, '\');
DBMS_OUTPUT.PUT_LINE('Number of slashes:' || (LENGTH(vFilePath)-LENGTH(vFilePath1)));
DBMS_OUTPUT.PUT_LINE('In 25 days it is:' || to_char(dDate25, 'MM-DD-YYYY'));
nNumber16 := 1/6;
DBMS_OUTPUT.PUT_LINE('The raw number is: ' || to_char(nNumber16, '9.999999999EEEE'));
DBMS_OUTPUT.PUT_LINE('The rounded number is: ' || round(nNumber16, 2));
END;
Thanks,

Answer 1

You can use the TRUNC(date) function if you want to always 'round down' to the current century (so a date in 2051 gives 2001); or the ROUND(date) function if you want to round properly (so 2051 gives 2101). Either way, with the CC format mask to get the first day of the century:
SQL> select round(sysdate + 25, 'CC') from dual;
TRUNC(SYSDATE+25,'C
-------------------
2001-01-01 00:00:00
So you can use:
ROUND(dDate25)
And you can then format that however you need; without any NLS assumptions:
DBMS_OUTPUT.PUT_LINE('Nearest Century: '
|| TO_CHAR(ROUND(dDate25, 'CC'), 'DD-MON-RR', 'NLS_DATE_LANGUAGE=ENGLISH'));

Answer 2

DECLARE
dDate25 DATE;
numYear NUMBER;
BEGIN
dDate25 := TO_DATE ('2016-01-27', 'YYYY-MM-DD');
SELECT (ROUND (TO_CHAR (dDate25, 'YYYY') / 100, 0) * 100) + 1
INTO numYear
FROM DUAL;
DBMS_OUTPUT.PUT_LINE('First year of the nearest century to ' || TO_CHAR(dDate25, 'YYYY-MM-DD') || ' is: ' || numYear);
dDate25 := TO_DATE ('2116-01-27', 'YYYY-MM-DD');
SELECT (ROUND (TO_CHAR (dDate25, 'YYYY') / 100, 0) * 100) + 1
INTO numYear
FROM DUAL;
DBMS_OUTPUT.PUT_LINE('First year of the nearest century to ' || TO_CHAR(dDate25, 'YYYY-MM-DD') || ' is: ' || numYear);
dDate25 := TO_DATE ('2051-01-27', 'YYYY-MM-DD');
SELECT (ROUND (TO_CHAR (dDate25, 'YYYY') / 100, 0) * 100) + 1
INTO numYear
FROM DUAL;
DBMS_OUTPUT.PUT_LINE('First year of the nearest century to ' || TO_CHAR(dDate25, 'YYYY-MM-DD') || ' is: ' || numYear);
END;
Output:
First year of the nearest century to 2016-01-27 is: 2001
First year of the nearest century to 2116-01-27 is: 2101
First year of the nearest century to 2051-01-27 is: 2101
ROUND (TO_CHAR (dDate25, 'YYYY') / 100, 0) * 100 gives you the nearest century i.e. it would round 2055 up to 2100. Adding +1 gives you the first year of the nearest century.
You can then TO_DATE(numYear || '-01-01', 'YYYY-MM-DD') to get January 1 of the first year of the nearest century if you need it in a date variable.

Answer 3

You mean decade instead of century, right? Otherwise your two end digits will always be "01" :-)
Corrected version (my previous one always returned 01, because it was rounding to the next century):
SELECT SUBSTR(FLOOR(to_char(systimestamp, 'YYYY')/10)*10,3,1) || 1 FROM dual
translated to your code:
decadeStart varchar2(10) := '01-JAN-' || SUBSTR(FLOOR(to_char(dDate25, 'YYYY')/10)*10,3,1) || 1;
DBMS_OUTPUT.PUT_LINE('The decade starts with: ' || decadeStart);