Follow us: Connect on YouTube Connect on YouTube Connect on YouTube

Pages

Friday, 1 April 2016

SQL Date Functions

Sysdate
Current_date
Current_timestamp
Systimestamp
Localtimestamp
Dbtimezone
Sessiontimezone
To_char
To_date
Add_months
Months_between
Next_day
Last_day
Extract
Greatest
Least
Round
Trunc
New_time
Coalesce

Oracle default date format is DD-MON-YY.
We can change the default format to our desired format by using the following command.

SQL> alter session set nls_date_format = ‘DD-MONTH-YYYY’;
        But this will expire once the session was closed.

a) SYSDATE

     This will give the current date and time.
      Ex:
           SQL> select sysdate from dual;

SYSDATE
-----------
24-DEC-06

b) CURRENT_DATE

     This will returns the current date in the session’s timezone.

      Ex:
           SQL> select current_date from dual;

CURRENT_DATE
------------------
     24-DEC-06

c) CURRENT_TIMESTAMP

     This will returns the current timestamp with the active time zone information.

      Ex:
           SQL> select current_timestamp from dual;

CURRENT_TIMESTAMP
---------------------------------------------------------------------------
24-DEC-06 03.42.41.383369 AM +05:30

d) SYSTIMESTAMP

     This will returns the system date, including fractional seconds and time zone of the database.

      Ex:
           SQL> select systimestamp from dual;
SYSTIMESTAMP
---------------------------------------------------------------------------
24-DEC-06 03.49.31.830099 AM +05:30

e) LOCALTIMESTAMP

     This will returns local timestamp in the active time zone information, with no time zone information shown.

      Ex:
                   SQL> select localtimestamp from dual;

LOCALTIMESTAMP
------------------------------------------
24-DEC-06 03.44.18.502874 AM

f) DBTIMEZONE

    This will returns the current database time zone in UTC format. (Coordinated Universal Time)

    Ex:
                   SQL> select dbtimezone from dual;

DBTIMEZONE
---------------
   -07:00 

g) SESSIONTIMEZONE

    This will returns the value of the current session’s time zone.

    Ex:
         SQL> select sessiontimezone from dual;

SESSIONTIMEZONE
---------------------------------
+05:30

       
       h) TO_CHAR

    This will be used to extract various date formats.
    The available date formats as follows.

    Syntax: to_char (date, format)
  
    DATE FORMATS
  
               D                      --         No of days in week
            DD                    --         No of days in month
            DDD                 --         No of days in year
            MM                   --         No of month
            MON                 --         Three letter abbreviation of month
            MONTH             --         Fully spelled out month
            RM                   --         Roman numeral month
            DY                    --         Three letter abbreviated day
            DAY                  --         Fully spelled out day
            Y                      --         Last one digit of the year
            YY                    --         Last two digits of the year
            YYY                  --         Last three digits of the year
            YYYY                --         Full four digit year
            SYYYY  --         Signed year
            I                       --         One digit year from ISO standard
            IY                     --         Two digit year from ISO standard
            IYY                   --         Three digit year from ISO standard
            IYYY                 --         Four digit year from ISO standard
            Y, YYY              --         Year with comma
            YEAR                --         Fully spelled out year
            CC                    --         Century
            Q                      --         No of quarters
            W                     --         No of weeks in month
            WW                  --         No of weeks in year
            IW                    --         No of weeks in year from ISO standard
            HH                    --         Hours
            MI                    --         Minutes
            SS                    --         Seconds
            FF                     --         Fractional seconds
            AM or PM         --         Displays AM or PM depending upon time of day
            A.M or P.M       --         Displays A.M or P.M depending upon time of day
            AD or BC          --         Displays AD or BC depending upon the date
            A.D or B.C        --         Displays AD or BC depending upon the date
            FM                    --         Prefix to month or day, suppresses padding of month or day
            TH                    --         Suffix to a number
            SP                    --         suffix to a number to be spelled out
            SPTH                --         Suffix combination of TH and SP to be both spelled out
            THSP                --         same as SPTH

Ex:
    SQL> select to_char(sysdate,'dd month yyyy hh:mi:ss am dy') from dual;

TO_CHAR(SYSDATE,'DD MONTH YYYYHH:MI
----------------------------------------------------
24 december  2006 02:03:23 pm sun    

    SQL> select to_char(sysdate,'dd month year') from dual;


TO_CHAR(SYSDATE,'DDMONTHYEAR')
-------------------------------------------------------
24 december  two thousand six

     SQL> select to_char(sysdate,'dd fmmonth year') from dual;

TO_CHAR(SYSDATE,'DD FMMONTH YEAR')
-------------------------------------------------------
24 december two thousand six

     SQL> select to_char(sysdate,'ddth DDTH') from dual;



TO_CHAR(S
------------
24th 24TH

     SQL> select to_char(sysdate,'ddspth DDSPTH') from dual;

TO_CHAR(SYSDATE,'DDSPTHDDSPTH
------------------------------------------
twenty-fourth TWENTY-FOURTH

     SQL> select to_char(sysdate,'ddsp Ddsp DDSP ') from dual;

TO_CHAR(SYSDATE,'DDSPDDSPDDSP')
------------------------------------------------
twenty-four Twenty-Four TWENTY-FOUR

i) TO_DATE

    This will be used to convert the string into data format.

    Syntax: to_date (date)

    Ex:
         SQL> select to_char(to_date('24/dec/2006','dd/mon/yyyy'), 'dd * month * day') from dual;

TO_CHAR(TO_DATE('24/DEC/20
--------------------------
24 * december  * Sunday

-- If you are not using to_char oracle will display output in default date format.
       
j) ADD_MONTHS

    This will add the specified months to the given date.

    Syntax: add_months (date, no_of_months)

    Ex:
          SQL> select add_months(to_date('11-jan-1990','dd-mon-yyyy'), 5) from dual;

ADD_MONTHS
----------------
11-JUN-90

SQL> select add_months(to_date('11-jan-1990','dd-mon-yyyy'), -5) from dual;

ADD_MONTH
---------------
11-AUG-89   
      
             If no_of_months is zero then it will display the same date.
      If no_of_months is null then it will display nothing.


k) MONTHS_BETWEEN

    This will give difference of months between two dates.

    Syntax: months_between (date1, date2)

    Ex:
         SQL> select months_between(to_date('11-aug-1990','dd-mon-yyyy'), to_date('11-jan- 1990','dd-mon-yyyy')) from dual;

MONTHS_BETWEEN(TO_DATE('11-AUG-1990','DD-MON-YYYY'),TO_DATE('11-JAN-1990','DD-MON-YYYY'))
-----------------------------------------------------------------------------
                                                                                        7
           SQL> select months_between(to_date('11-jan-1990','dd-mon-yyyy'), to_date('11-aug-1990','dd-mon-yyyy')) from dual;

MONTHS_BETWEEN(TO_DATE('11-JAN-1990','DD-MON-YYYY'),TO_DATE('11-AUG-1990','DD-MON-YYYY'))
----------------------------------------------------------------------------
                                                                                       -7

l) NEXT_DAY

    This will produce next day of the given day from the specified date.

    Syntax: next_day (date,  day)

    Ex:
         SQL> select next_day(to_date('24-dec-2006','dd-mon-yyyy'),'sun') from dual;

NEXT_DAY(
-------------
31-DEC-06

-- If the day parameter is null then it will display nothing.

m) LAST_DAY

    This will produce last day of the given date.

    Syntax: last_day (date)

    Ex:
         SQL> select last_day(to_date('24-dec-2006','dd-mon-yyyy'),'sun') from dual;

LAST_DAY(
-------------
31-DEC-06



n) EXTRACT

    This is used to extract a portion of the date value.

    Syntax: extract ((year | month | day | hour | minute | second), date)

    Ex:
         SQL> select extract(year from sysdate) from dual;
EXTRACT(YEARFROMSYSDATE)
------------------------------------
                    2006

-- You can extract only one value at a time.

o) GREATEST

     This will give the greatest date.

     Syntax: greatest (date1, date2, date3 … daten)

     Ex:
         SQL> select greatest(to_date('11-jan-90','dd-mon-yy'),to_date('11-mar-90','dd-mon- yy'),to_date('11-apr-90','dd-mon-yy')) from dual;

  GREATEST(
  -------------
   11-APR-90

p) LEAST

     This will give the least date.

     Syntax: least (date1, date2, date3 … daten)

     Ex:
         SQL> select least(to_date('11-jan-90','dd-mon-yy'),to_date('11-mar-90','dd-mon-yy'),to_date('11-apr-90','dd-mon-yy')) from dual;

  LEAST(
  -------------
   11-JAN-90

q) ROUND

    Round will rounds the date to which it was equal to or greater than the given date.

    Syntax: round (date, (day | month | year))


    If the second parameter was year then round will checks the month of the given date in the following ranges.
          
             JAN      --          JUN    
            JUL       --          DEC

    If the month falls between JAN and JUN then it returns the first day of the current year.
    If the month falls between JUL and DEC then it returns the first day of the next year.

    If the second parameter was month then round will checks the day of the given date in the
    following ranges.

            1          --         15      
            16        --         31

    If the day falls between 1 and 15 then it returns the first day of the current month.
    If the day falls between 16 and 31 then it returns the first day of the next month.

    If the second parameter was day then round will checks the week day of the given date in 
    the following ranges.

            SUN      --          WED
            THU      --          SUN
    If the week day falls between SUN and WED then it returns the previous Sunday.
    If the weekday falls between THU and SUN then it returns the next Sunday.

          If the second parameter was null then it returns nothing.
If the you are not specifying the second parameter then round will resets the time to the beginning of the current day in case of user specified date.
If the you are not specifying the second parameter then round will resets the time to the beginning of the next day in case of sysdate.
 
    Ex:
         SQL> select round(to_date('24-dec-04','dd-mon-yy'),'year'), round(to_date('11-mar-06','dd-mon-yy'),'year') from dual;

ROUND(TO_ ROUND(TO_
------------   ---------------
01-JAN-05   01-JAN-06
           SQL> select round(to_date('11-jan-04','dd-mon-yy'),'month'),
                 round(to_date('18-jan-04','dd-mon-yy'),'month') from dual; 

ROUND(TO_ ROUND(TO_
-------------  ---------------
01-JAN-04    01-FEB-04

           SQL> select round(to_date('26-dec-06','dd-mon-yy'),'day'), round(to_date('29-dec-06','dd-mon-yy'),'day') from dual;
 
ROUND(TO_ ROUND(TO_
--------------  --------------
24-DEC-06     31-DEC-06

           SQL> select to_char(round(to_date('24-dec-06','dd-mon-yy')), 'dd mon yyyy hh:mi:ss am') from dual;

TO_CHAR(ROUND(TO_DATE('
---------------------------------
24 dec 2006 12:00:00 am
r) TRUNC

    Trunc will chops off the date to which it was equal to or less than the given date.

    Syntax: trunc (date, (day | month | year))

If the second parameter was year then it always returns the first day of the current year.
If the second parameter was month then it always returns the first day of the current month.
If the second parameter was day then it always returns the previous sunday.
If the second parameter was null then it returns nothing.
If the you are not specifying the second parameter then trunk will resets the time to the begining of the current day.

    Ex:
         SQL> select trunc(to_date('24-dec-04','dd-mon-yy'),'year'), trunc(to_date('11-mar-06','dd-mon-yy'),'year') from dual;

TRUNC(TO_ TRUNC(TO_
-------------  --------------
01-JAN-04    01-JAN-06

          SQL> select trunc(to_date('11-jan-04','dd-mon-yy'),'month'), trunc(to_date('18-jan-04','dd-mon-yy'),'month') from dual;

TRUNC(TO_ TRUNC(TO_
-------------  -------------
01-JAN-04    01-JAN-04
 
  SQL> select trunc(to_date('26-dec-06','dd-mon-yy'),'day'), trunc(to_date('29-dec-06','dd-mon-yy'),'day') from dual;

TRUNC(TO_ TRUNC(TO_
-------------  --------------
24-DEC-06 24-DEC-06
        
          SQL> select to_char(trunc(to_date('24-dec-06','dd-mon-yy')), 'dd mon yyyy hh:mi:ss am') from dual;

TO_CHAR(TRUNC(TO_DATE('
---------------------------------
24 dec 2006 12:00:00 am

s) NEW_TIME

     This will give the desired timezone’s date and time.

     Syntax: new_time (date, current_timezone, desired_timezone)

     Available timezones are as follows.

    TIMEZONES

                        AST/ADT         --         Atlantic standard/day light time
                        BST/BDT          --         Bering standard/day light time
                        CST/CDT          --         Central standard/day light time
                        EST/EDT          --         Eastern standard/day light time
                        GMT                 --         Greenwich mean time
                        HST/HDT         --         Alaska-Hawaii standard/day light time
                        MST/MDT         --         Mountain standard/day light time
                        NST                 --          Newfoundland standard time
                        PST/PDT          --         Pacific standard/day light time
                        YST/YDT          --         Yukon standard/day light time

    Ex:
        SQL> select to_char(new_time(sysdate,'gmt','yst'),'dd mon yyyy hh:mi:ss am') from dual;

TO_CHAR(NEW_TIME(SYSDAT
-----------------------------------
24 dec 2006 02:51:20 pm

          SQL> select to_char(new_time(sysdate,'gmt','est'),'dd mon yyyy hh:mi:ss am') from dual;
TO_CHAR(NEW_TIME(SYSDAT
-----------------------
24 dec 2006 06:51:26 pm

t) COALESCE

    This will give the first non-null date.

    Syntax: coalesce (date1, date2, date3 … daten)

    Ex:
         SQL> select coalesce('12-jan-90','13-jan-99'), coalesce(null,'12-jan-90','23-mar-98',null) from dual;

COALESCE( COALESCE(
-------------  ------------
12-jan-90     12-jan-90

MISCELLANEOUS FUNCTIONS

Uid
User
Vsize
Rank
Dense_rank

a) UID

     This will returns the integer value corresponding to the user currently logged in.

     Ex:
          SQL> select uid from dual;

       UID
     -------
       319

b) USER

     This will returns the login’s user name.

     Ex:
           SQL> select user from dual;

USER
----------------
SAKETH


c) VSIZE
     This will returns the number of bytes in the expression.

     Ex:
          SQL> select vsize(123), vsize('computer'), vsize('12-jan-90') from dual;

VSIZE(123) VSIZE('COMPUTER') VSIZE('12-JAN-90')
-------------  -----------------------  ----------------------
         3                         8                                  9

d) RANK

     This will give the non-sequential ranking.

     Ex:
          SQL> select rownum,sal from (select sal from emp order by sal desc);

    ROWNUM    SAL
    ---------- ----------
         1       5000
         2       3000
         3       3000
         4       2975
         5       2850
         6       2450
         7       1600
         8       1500
         9       1300
        10       1250
        11       1250
        12       1100
        13       1000
        14        950
        15        800

     SQL> select rank(2975) within group(order by sal desc) from emp;

RANK(2975)WITHINGROUP(ORDERBYSALDESC)
---------------------------------------------------------
                                    4
d) DENSE_RANK

     This will give the sequential ranking.
   
Ex:
     SQL> select dense_rank(2975) within group(order by sal desc) from emp;

DENSE_RANK(2975)WITHINGROUP(ORDERBYSALDESC)
-----------------------------------------------------------------
                                          3

CONVERSION FUNCTIONS

Bin_to_num
Chartorowid
Rowidtochar
To_number
To_char
To_date
a) BIN_TO_NUM

     This will convert the binary value to its numerical equivalent.

     Syntax: bin_to_num( binary_bits)

     Ex:
          SQL> select bin_to_num(1,1,0) from dual;

BIN_TO_NUM(1,1,0)
------------------------
                6
 If all the bits are zero then it produces zero.
 If all the bits are null then it produces an error.

b) CHARTOROWID

     This will convert a character string to act like an internal oracle row identifier or rowid.

c) ROWIDTOCHAR

    This will convert an internal oracle row identifier or rowid to character string.

d) TO_NUMBER

    This will convert a char or varchar to number.

e) TO_CHAR

    This will convert a number or date to character string.

f) TO_DATE



    This will convert a number, char or varchar to a date.
Share this article :

0 comments:

Post a Comment