Oracle Date Functions

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Oracle Date Functions

Version 11.1

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Date

Current Date

CURRENT_DATE
SYSDATE

SELECT TO_CHAR(CURRENT_DATE , 'DD-MON-YYYY HH:MI:SS') FROM dual;

SELECT TO_CHAR(SYSDATE , 'DD-MON-YYYY HH:MI:SS') FROM dual;

Formats

Day	Month	Year	Fill Mode	Julian Date
D	MM	YY	FM	J
DD	MON	YYYY
DDTH		RR
DAY		RRRR

+ AND -

SELECT SYSDATE + 1 FROM dual;

SELECT SYSDATE - 1 FROM dual;

ADD_MONTHS

Add A Month To A Date

ADD_MONTHS(<date>, <number of months_integer>

SELECT add_months (SYSDATE, 2) FROM dual;

-- but be aware of what it is doing
SELECT add_months (TO_DATE('27-JAN-2007'), 1) FROM dual;

SELECT add_months (TO_DATE('28-JAN-2007'), 1) FROM dual;

SELECT add_months (TO_DATE('29-JAN-2007'), 1) FROM dual;

SELECT add_months (TO_DATE('30-JAN-2007'), 1) FROM dual;

SELECT add_months (TO_DATE('31-JAN-2007'), 1) FROM dual;

SELECT add_months (TO_DATE('01-FEB-2007'), 1) FROM dual;

CURRENT_DATE

Returns the current date of the server as a value in the Gregorian calendar of datatype DATE

col sessiontimezone format a30

SELECT sessiontimezone, current_date
FROM dual;

ALTER SESSION SET TIME_ZONE = '-5:0';

SELECT sessiontimezone, current_date
FROM dual;

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';

SELECT sessiontimezone, current_date
FROM dual;

ALTER SESSION SET TIME_ZONE = '-7:0';

SELECT sessiontimezone, current_date
FROM dual;

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY';

DUMP

Returns The Number Of Bytes And Datatype Of A Value

DUMP(<value>)

SELECT DUMP (SYSDATE) FROM dual;

GREATEST

Return the Latest Date

LEAST(<date>, <date>, <date>, ...)

CREATE TABLE t (
datecol1 DATE,
datecol2 DATE,
datecol3 DATE)
PCTFREE 0;

INSERT INTO t VALUES (SYSDATE+23, SYSDATE-10, SYSDATE-24);
INSERT INTO t VALUES (SYSDATE-15, SYSDATE, SYSDATE+15);
INSERT INTO t VALUES (SYSDATE-7, SYSDATE-18, SYSDATE-9);
COMMIT;

SELECT * FROM t;

SELECT GREATEST (datecol1, datecol2, datecol3)
FROM t;

INTERVAL

Interval to adjust date-time

INTERVAL '<integer>' <unit>

SELECT TO_CHAR(SYSDATE, 'HH:MI:SS')
FROM dual;

SELECT TO_CHAR(SYSDATE + INTERVAL '10' MINUTE , 'HH:MI:SS')
FROM dual;

SELECT TO_CHAR(SYSDATE - INTERVAL '10' MINUTE , 'HH:MI:SS')
FROM dual;

LAST_DAY

Returns The Last Date Of A Month

LAST_DAY(<date>)

SELECT * FROM t;

SELECT LAST_DAY (datecol1) FROM t;

LEAST

Return the Earliest Date

LEAST(<date>, <date>, <date>, ...)

SELECT * FROM t;

SELECT LEAST (datecol1, datecol2, datecol3) FROM t;

LENGTH

Returns length in characters

LENGTH(<date>)

SELECT LENGTH (last_ddl_time) FROM user_objects;

LENGTHB

Returns length in bytes

LENGTHB(<date>)

SELECT LENGTHB (last_ddl_time) FROM user_objects;

Note: Additional forms of LENGTH (LENGTHC, LENGTH2, and LENGTH4) are also available.

MAX

Return the Latest Date

MAX(<date>)

SELECT * FROM t;

SELECT MAX (datecol1) FROM t;

MIN

Return the Earliest Date

MIN(<date>)

SELECT * FROM t;

SELECT MIN (datecol1) FROM t;

MONTHS_BETWEEN

Returns The Months Separating Two Dates

MONTHS_BETWEEN(<latest_date>, <earliest_date>)

SELECT MONTHS_BETWEEN (SYSDATE+365, SYSDATE-365) FROM dual;

SELECT MONTHS_BETWEEN (SYSDATE-365, SYSDATE+365) FROM dual;

NEW_TIME

Returns the date and time in time zone zone2 when date and time in time zone zone1 are date

Before using this function, you must set the NLS_DATE_FORMAT parameter to display 24-hour time.

SELECT NEW_TIME (TO_DATE('11-10-99 01:23:45',
'MM-DD-YY HH24:MI:SS'), 'AST', 'PST') "New Date and Time"
FROM dual;

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';

SELECT NEW_TIME (TO_DATE('11-10-99 01:23:45',
'MM-DD-YY HH24:MI:SS'), 'AST', 'PST') "New Date and Time"
FROM dual;

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY';

NEXT_DAY

Date of next specified date following a date

NEXT_DAY(<date>, <day of the week>)

Options are SUN, MON, TUE, WED, THU, FRI, and SAT

SELECT NEXT_DAY (SYSDATE, 'FRI') FROM dual;

ROUND

Returns date rounded to the unit specified by the format model. If you omit the format, the date is rounded to the nearest day

ROUND(<date_value>, <format>)

SELECT ROUND (TO_DATE('27-OCT-00'),'YEAR') NEW_YEAR
FROM dual;

Spelled Out Using TO_CHAR

Spelled Demo

DDSP

HH24SP

MISP

MMSP

SSSP

SELECT TO_CHAR(TO_DATE('10:30:18', 'HH24:MI:SS'), 'HH24SP :MISP:SSSP ')
FROM dual;

SELECT TO_CHAR(TO_DATE('01-JAN-2008', 'DD-MON-YYYY'), 'DDSP -MONTH-YYYYSP ')
FROM dual;

SELECT TO_CHAR(TO_DATE('01-JAN-2008', 'DD-MM-YYYY'), 'DDSP -MMSP -YYYYSP ')
FROM dual;

SELECT TO_CHAR(TO_DATE(sal,'J'), 'JSP')
FROM emp;

SYSDATE

Returns the current session DateTime

SYSDATE

SELECT SYSDATE FROM dual;

TRUNC

Convert a date to the date at midnight

TRUNC(<date_time>)

CREATE TABLE t (
datecol DATE);

INSERT INTO t (datecol) VALUES (SYSDATE);

INSERT INTO t (datecol) VALUES (TRUNC (SYSDATE));

INSERT INTO t (datecol) VALUES (TRUNC (SYSDATE, 'HH '));

INSERT INTO t (datecol) VALUES (TRUNC (SYSDATE, 'MI '));

COMMIT;

SELECT TO_CHAR(datecol, 'DD-MON-YYYY HH:MI:SS')
FROM t;

Selectively remove part of the date information

Special thanks to Dave Hayes for reminding me of this.

TRUNC(<date_time>, '<format>')

SELECT TO_CHAR(SYSDATE, 'DD-MON-YYYY HH:MI:SS')
FROM dual;

-- first day of the month
SELECT TO_CHAR(TRUNC (SYSDATE, 'MM' ), 'DD-MON-YYYY HH:MI:SS')
FROM dual;

SELECT TO_CHAR(TRUNC (SYSDATE, 'MON' ), 'DD-MON-YYYY HH:MI:SS')
FROM dual;

SELECT TO_CHAR(TRUNC (SYSDATE, 'MONTH' ), 'DD-MON-YYYY HH:MI:SS')
FROM dual;

-- first day of the year
SELECT TO_CHAR(TRUNC (SYSDATE, 'YYYY' ), 'DD-MON-YYYY HH:MI:SS')
FROM dual;

SELECT TO_CHAR(TRUNC (SYSDATE, 'YEAR' ), 'DD-MON-YYYY HH:MI:SS')
FROM dual;

Dates in WHERE Clause Joins

SELECT SYSDATE FROM dual;

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';

SELECT SYSDATE FROM dual;

/

/

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY';

CREATE TABLE t (
datecol DATE);

INSERT INTO t
(datecol)
VALUES
(SYSDATE);

SELECT * FROM t;

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';

SELECT * FROM t;

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY';

SELECT * FROM t;

SELECT SYSDATE FROM dual;

SELECT * FROM t
WHERE datecol = SYSDATE;

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';

SELECT * FROM t;

SELECT SYSDATE FROM dual;

SELECT TRUNC (SYSDATE) FROM dual;

SELECT * FROM t
WHERE TRUNC (datecol) = TRUNC (SYSDATE);

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY';

VSIZE

Returns The Number Of Bytes Required By A Value

VSIZE(e IN DATE) RETURN NUMBER

SELECT VSIZE (SYSDATE) FROM dual;

Date Calculations

Returns A Day A Specified Number Of Days In The Future Skipping Weekends

CREATE OR REPLACE FUNCTION business_date (start_date DATE,
Days2Add NUMBER) RETURN DATE IS
Counter NATURAL := 0;
CurDate DATE := start_date;
DayNum   POSITIVE;
SkipCntr NATURAL := 0;
BEGIN
WHILE Counter < Days2Add LOOP
    CurDate := CurDate+1;
    DayNum := TO_CHAR(CurDate, 'D');

    IF DayNum BETWEEN 2 AND 6 THEN
      Counter := Counter + 1;
    ELSE
      SkipCntr := SkipCntr + 1;
    END IF;
END LOOP;
RETURN start_date + Counter + SkipCntr;
END business_date;
/

Business Date function, above, enhanced by Larry Benton to handle negative values for the days2add parameter.

CREATE OR REPLACE FUNCTION business_date (start_date DATE,
days2add NUMBER) RETURN DATE IS
Counter NATURAL := 0;
CurDate DATE := start_date;
DayNum POSITIVE;
SkipCntr NATURAL := 0;
Direction INTEGER := 1;   -- days after start_date
BusinessDays NUMBER := Days2Add;
BEGIN
IF Days2Add < 0 THEN
    Direction := - 1; -- days before start_date
    BusinessDays := (-1) * BusinessDays;
END IF;

WHILE Counter < BusinessDays LOOP
    CurDate := CurDate + Direction;
    DayNum := TO_CHAR( CurDate, 'D');

    IF DayNum BETWEEN 2 AND 6 THEN
      Counter := Counter + 1;
    ELSE
      SkipCntr := SkipCntr + 1;
    END IF;
END LOOP;

RETURN start_date + (Direction * (Counter + SkipCntr));
END business_date;
/

Returns The First Day Of A Month

CREATE OR REPLACE FUNCTION fday_ofmonth(value_in DATE)
RETURN DATE IS
vMo VARCHAR2(2);
vYr VARCHAR2(4);
BEGIN
vMo := TO_CHAR(value_in, 'MM');
vYr := TO_CHAR(value_in, 'YYYY');
RETURN TO_DATE(vMo || '-01-' || vYr, 'MM-DD-YYYY');
EXCEPTION
WHEN OTHERS THEN
RETURN TO_DATE('01-01-1900', 'MM-DD-YYYY');
END fday_ofmonth;
/

Time Calculations

Returns The Number Of Seconds Between Two Date-Time Values

CREATE OR REPLACE FUNCTION time_diff (
DATE_1 IN DATE, DATE_2 IN DATE) RETURN NUMBER IS

NDATE_1   NUMBER;
NDATE_2   NUMBER;
NSECOND_1 NUMBER(5,0);
NSECOND_2 NUMBER(5,0);

BEGIN
   -- Get Julian date number from first date (DATE_1)
NDATE_1 := TO_NUMBER(TO_CHAR(DATE_1, 'J'));

   -- Get Julian date number from second date (DATE_2)
NDATE_2 := TO_NUMBER(TO_CHAR(DATE_2, 'J'));

   -- Get seconds since midnight from first date (DATE_1)
NSECOND_1 := TO_NUMBER(TO_CHAR(DATE_1, 'SSSSS'));

   -- Get seconds since midnight from second date (DATE_2)
NSECOND_2 := TO_NUMBER(TO_CHAR(DATE_2, 'SSSSS'));

RETURN (((NDATE_2 - NDATE_1) * 86400)+(NSECOND_2 - NSECOND_1));
END time_diff;
/

Calculating time from seconds

Posted by John K. Hinsdale
12/30/06 to c.d.o.misc

SELECT DECODE(FLOOR(999999/86400), 0, '',
FLOOR(999999/86400) || ' day(s), ') ||
TO_CHAR(TO_DATE(MOD(999999, 86400),'SSSSS'), 'HH24:MI:SS') AS elapsed
FROM dual;

Obtain counts per ten minute increment

Posted by Michele Cadot
03/09/08 to c.d.o.misc

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';

SELECT TRUNC(SYSDATE) + dbms_random.value(0,86400)/86400
FROM dual
CONNECT BY LEVEL <= 10;

WITH data AS (
SELECT TRUNC(SYSDATE)+dbms_random.value(0,86400)/86400 h
FROM dual
CONNECT BY LEVEL <= 10)
SELECT TO_CHAR(h ,'DD/MM/YYYY HH24:MI:SS') h , TO_CHAR(TRUNC(h )
+ TRUNC(TO_CHAR(h ,'SSSSS')/600)/144, 'DD/MM/YYYY HH24:MI:SS') "10m"
FROM data
ORDER BY h ;

http://blog.youkuaiyun.com/tingqier/archive/2008/10/08/3033884.aspx

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