# FUNCTIONS

Functions can be categorized as follows.

Ø  Single row functions

Ø  Group functions

SINGLE ROW FUNCTIONS

Single row functions can be categorized into five. These will be applied for each row and produces individual output for each row.

Ø  Numeric functions

Ø  String functions

Ø  Date functions

Ø  Miscellaneous functions

Ø  Conversion functions

NUMERIC FUNCTIONS

Ø  Abs

Ø  Sign

Ø  Sqrt

Ø  Mod

Ø  Nvl

Ø  Power

Ø  Exp

Ø  Ln

Ø  Log

Ø  Ceil

Ø  Floor

Ø  Round

Ø  Trunk

Ø  Bitand

Ø  Greatest

Ø  Least

Ø  Coalesce

a) ABS

Absolute value is the measure of the magnitude of value.

Absolute value is always a positive number.

Syntax: abs (value)

Ex:

SQL> select abs(5), abs(-5), abs(0), abs(null) from dual;

 ABS(5) ABS(-5) ABS(0) ABS(NULL) ---------- ---------- ---------- ------------- 5 -5 0

b) SIGN

Sign gives the sign of a value.

Syntax: sign (value)

Ex:

SQL> select sign(5), sign(-5), sign(0), sign(null) from dual;

 SIGN(5) SIGN(-5) SIGN(0) SIGN(NULL) ---------- ---------- ---------- -------------- 1 -1 0

c) SQRT

This will give the square root of the given value.

Syntax: sqrt (value)   -- here value must be positive.

Ex:

SQL> select sqrt(4), sqrt(0), sqrt(null), sqrt(1) from dual;

 SQRT(4) SQRT(0) SQRT(NULL) SQRT(1) ---------- ---------- --------------- ---------- 2 0 1

d) MOD

This will give the remainder.

Syntax: mod (value, divisor)

Ex:

SQL> select mod(7,4), mod(1,5), mod(null,null), mod(0,0), mod(-7,4) from dual;

 MOD(7,4) MOD(1,5) MOD(NULL,NULL) MOD(0,0) MOD(-7,4) ------------ ---------- --------------------- ----------- ------------- 3 1 0 -3

e) NVL

This will substitutes the specified value in the place of null values.

Syntax: nvl (null_col, replacement_value)

 Ex: SQL> select * from student; -- here for 3rd row marks value is null NO NAME MARKS --- ------- --------- 1 a 100 2 b 200 3 c

SQL> select no, name, nvl(marks,300) from student;

NO NAME NVL(MARKS,300)

 --- ------- --------------------- 1 a 100 2 b 200 3 c 300

SQL> select nvl(1,2), nvl(2,3), nvl(4,3), nvl(5,4) from dual;

 NVL(1,2) NVL(2,3) NVL(4,3) NVL(5,4) ---------- ---------- ---------- ---------- 1 2 4 5

SQL> select nvl(0,0), nvl(1,1), nvl(null,null), nvl(4,4) from dual;

 NVL(0,0) NVL(1,1) NVL(null,null) NVL(4,4) ---------- ---------- ----------------- ---------- 0 1 4

f) POWER

Power is the ability to raise a value to a given exponent.

Syntax: power (value, exponent)

Ex:

SQL> select power(2,5), power(0,0), power(1,1), power(null,null), power(2,-5) from dual;

POWER(2,5) POWER(0,0) POWER(1,1) POWER(NULL,NULL) POWER(2,-5)

 -------------- -------------- ----- --------- ----------------------- --------------- 32 1 1 .03125

g) EXP

This will raise e value to the give power.

Syntax: exp (value)

Ex:

SQL> select exp(1), exp(2), exp(0), exp(null), exp(-2) from dual;

 EXP(1) EXP(2) EXP(0) EXP(NULL) EXP(-2) -------- --------- -------- ------------- ---------- 2.71828183 7.3890561 1 .135335283

h) LN

This is based on natural or base e logarithm.

Syntax: ln (value)

Ex:

-- here value must be greater than zero which is positive only.

SQL> select ln(1), ln(2), ln(null) from dual;

 LN(1) LN(2) LN(NULL) ------- ------- ------------ 0 .693147181

Ln and Exp are reciprocal to each other.

EXP (3) = 20.0855369

LN (20.0855369) = 3

i) LOG

This is based on 10 based logarithm.

Syntax: log (10, value) -- here value must be greater than zero which is positive only.

Ex:

SQL> select log(10,100), log(10,2), log(10,1), log(10,null) from dual;

LOG(10,100) LOG(10,2) LOG(10,1) LOG(10,NULL)

 --------------- ----------- ------------ ----------------- 2 .301029996 0

LN (value) = LOG (EXP(1), value)

SQL> select ln(3), log(exp(1),3) from dual;

 LN(3) LOG(EXP(1),3) ------- ----------------- 1.09861229 1.09861229

j) CEIL

This will produce a whole number that is greater than or equal to the specified value.

Syntax: ceil (value)

Ex:

SQL> select ceil(5), ceil(5.1), ceil(-5), ceil( -5.1), ceil(0), ceil(null) from dual;

 CEIL(5) CEIL(5.1) CEIL(-5) CEIL(-5.1) CEIL(0) CEIL(NULL) --------- ----------- ---------- ------------ -------- -------------- 5 6 -5 -5 0

k) FLOOR

This will produce a whole number that is less than or equal to the specified value.

Syntax: floor (value)

Ex:

SQL> select floor(5), floor(5.1), floor(-5), floor( -5.1), floor(0), floor(null) from dual;

 FLOOR(5) FLOOR(5.1) FLOOR(-5) FLOOR(-5.1) FLOOR(0) FLOOR(NULL) ----------- ------------- ------------ -------------- ----------- ---------------- 5 5 -5 -6 0

l) ROUND

This will rounds numbers to a given number of digits of precision.

Syntax: round (value, precision)

Ex:

SQL> select round(123.2345), round(123.2345,2), round(123.2354,2) from dual;

ROUND(123.2345) ROUND(123.2345,0) ROUND(123.2345,2) ROUND(123.2354,2)

 --------------------- ------------------------ ----------------------- ----------------------- 123 123 123.23 123.24

SQL> select round(123.2345,-1), round(123.2345,-2), round(123.2345,-3), round(123.2345,-4) from dual;

ROUND(123.2345,-1) ROUND(123.2345,-2) ROUND(123.2345,-3) ROUND(123.2345,-4)

 ------------------------ ------------------------- ------------------------ ------------------------ 120 100 0 0

SQL> select round(123,0), round(123,1), round(123,2) from dual;

ROUND(123,0) ROUND(123,1) ROUND(123,2)

 ----------------- ----------------- ---------------- 123 123 123

SQL> select round(-123,0), round(-123,1), round(-123,2) from dual;

ROUND(-123,0) ROUND(-123,1) ROUND(-123,2)

 ------------------ ----------------- ------------------- -123 -123 -123

SQL> select round(123,-1), round(123,-2), round(123,-3), round(-123,-1), round(-123,-2), round(-123,-3) from dual;

ROUND(123,-1) ROUND(123,-2) ROUND(123,-3) ROUND(-123,-1) ROUND(-123,-2) ROUND(-123,-3)

------------- ------------- ------------- -------------- -------------- --------------

120            100               0                 -120                 -100                0

SQL> select round(null,null), round(0,0), round(1,1), round(-1,-1), round(-2,-2) from dual;

ROUND(NULL,NULL) ROUND(0,0) ROUND(1,1) ROUND(-1,-1) ROUND(-2,-2)

 ----------------------- -------------- -------------- ---------------- ---------------- 0 1 0 0

m) TRUNC

This will truncates or chops off digits of precision from a number.

Syntax: trunc (value, precision)

Ex:

SQL> select trunc(123.2345), trunc(123.2345,2), trunc(123.2354,2) from dual;

TRUNC(123.2345) TRUNC(123.2345,2) TRUNC(123.2354,2)

 --------------------- ----------------------- ----------------------- 123 123.23 123.23

SQL> select trunc(123.2345,-1), trunc(123.2345,-2), trunc(123.2345,-3), trunc(123.2345,-4) from dual;

TRUNC(123.2345,-1) TRUNC(123.2345,-2) TRUNC(123.2345,-3) TRUNC(123.2345,-4)

 ------------------------ ------------------------ ----------------------- ------------------------ 120 100 0 0

SQL> select trunc(123,0), trunc(123,1), trunc(123,2) from dual;

TRUNC(123,0) TRUNC(123,1) TRUNC(123,2)

 ---------------- ---------------- ----------------- 123 123 123

SQL> select trunc(-123,0), trunc(-123,1), trunc(-123,2) from dual;

TRUNC(-123,0) TRUNC(-123,1) TRUNC(-123,2)

 ----------------- ----------------- ----------------- -123 -123 -123

SQL> select trunc(123,-1), trunc(123,-2), trunc(123,-3), trunc(-123,-1), trunc(-123,2), trunc(-123,-3) from dual;

TRUNC(123,-1) TRUNC(123,-2) TRUNC(123,-3) TRUNC(-123,-1) TRUNC(-123,2) TRUNC(-123,-3)
------------- ------------- ------------- -------------- ------------- --------------

120            100               0                     -120           -123                0

SQL> select trunc(null,null), trunc(0,0), trunc(1,1), trunc(-1,-1), trunc(-2,-2) from dual;

TRUNC(NULL,NULL) TRUNC(0,0) TRUNC(1,1) TRUNC(-1,-1) TRUNC(-2,-2)

 ----------------------- ------------- ------------- --------------- ---------------- 0 1 0 0

n) BITAND

This will perform bitwise and operation.

Syntax: bitand (value1, value2)

Ex:

SQL> select bitand(2,3), bitand(0,0), bitand(1,1), bitand(null,null), bitand(-2,-3) from dual;

 BITAND(2,3) BITAND(0,0) BITAND(1,1) BITAND(NULL,NULL) BITAND(-2,-3) -------------- --------------- -------------- ------------------------ ----------------- 2 0 1 -4

o) GREATEST

This will give the greatest number.

Syntax: greatest (value1, value2, value3 … valuen)

Ex:

SQL> select greatest(1, 2, 3), greatest(-1, -2, -3) from dual;

GREATEST(1,2,3) GREATEST(-1,-2,-3)

-------------------- -----------------------

3                            -1

Ø  If all the values are zeros then it will display zero.

Ø  If all the parameters are nulls then it will display nothing.

Ø  If any of the parameters is null it will display nothing.

p)  LEAST

This will give the least number.

Syntax: least (value1, value2, value3 … valuen)

Ex:

SQL> select least(1, 2, 3), least(-1, -2, -3) from dual;

LEAST(1,2,3)          LEAST(-1,-2,-3)

-------------------- -----------------------

1                            -3

Ø  If all the values are zeros then it will display zero.

Ø  If all the parameters are nulls then it will display nothing.

Ø  If any of the parameters is null it will display nothing.

q) COALESCE

This will return first non-null value.

Syntax: coalesce (value1, value2, value3 … valuen)

Ex:

SQL> select coalesce(1,2,3), coalesce(null,2,null,5) from dual;

COALESCE(1,2,3) COALESCE(NULL,2,NULL,5)

 ------------------- ------------------------------- 1 2

STRING FUNCTIONS

Ø  Initcap

Ø  Upper

Ø  Lower

Ø  Length

Ø  Ltrim

Ø  Rtrim

Ø  Trim

Ø  Translate

Ø  Replace

Ø  Soundex

Ø  Concat ( ‘ || ‘ Concatenation operator)

Ø  Ascii

Ø  Chr

Ø  Substr

Ø  Instr

Ø  Decode

Ø  Greatest

Ø  Least

Ø  Coalesce

a) INITCAP

This will capitalize the initial letter of the string.

Syntax: initcap (string)

Ex:

SQL> select initcap('computer') from dual;

INITCAP

-----------

Computer

b) UPPER

This will convert the string into uppercase.

Syntax: upper (string)

Ex:

SQL> select upper('computer') from dual; UPPER
-----------

COMPUTER

c) LOWER

This will convert the string into lowercase.

Syntax: lower (string)

Ex:

SQL> select lower('COMPUTER') from dual;

LOWER

-----------

computer

d) LENGTH

This will give length of the string.

Syntax: length (string)

Ex:

SQL> select length('computer') from dual;

LENGTH

-----------

8

This will allows you to pad the right side of a column with any set of characters.

Ex:

---------------------- ----------------------

computer*******    computer*#*#*#*

--  Default padding character was blank space.

This will allows you to pad the left side of a column with any set of characters.

Ex:

---------------------  ---------------------

*******computer  *#*#*#*computer

--  Default padding character was blank space.

g)  LTRIM

This will trim off unwanted characters from the left end of string.

Syntax: ltrim (string [,unwanted_chars])

Ex:

SQL> select ltrim('computer','co'), ltrim('computer','com') from dual;

LTRIM( LTRIM

-------- ---------

mputer  puter

SQL> select ltrim('computer','puter'), ltrim('computer','omputer') from dual;

LTRIM('C  LTRIM('C

----------  ----------

computer  computer

--  If you haven’t specify any unwanted characters it will display entire string.

h)  RTRIM

This will trim off unwanted characters from the right end of string.

Syntax: rtrim (string [, unwanted_chars])

Ex:

SQL> select rtrim('computer','er'), rtrim('computer','ter') from dual; RTRIM( RTRIM

-------- ---------

comput  compu

SQL> select rtrim('computer','comput’), rtrim('computer','compute') from dual;

RTRIM('C  RTRIM('C

----------  ----------

computer  computer

-- If you haven’t specify any unwanted characters it will display entire string.

i) TRIM

This will trim off unwanted characters from the both sides of string.

Syntax: trim (unwanted_chars from string)

Ex:

SQL> select trim( 'i' from 'indiani') from dual;

TRIM(

-----

ndian

SQL> select trim( leading'i' from 'indiani') from dual;          -- this will work as LTRIM

TRIM(L

------

ndiani

SQL> select trim( trailing'i' from 'indiani') from dual;          -- this will work as RTRIM

TRIM(T

------

Indian

j) TRANSLATE

This will replace the set of characters, character by character.

Syntax: translate (string, old_chars, new_chars)

Ex:

SQL> select translate('india','in','xy') from dual;

TRANS

--------

xydxa

k) REPLACE

This will replace the set of characters, string by string.

Syntax: replace (string, old_chars [, new_chars])

Ex:

SQL> select replace('india','in','xy'), replace(‘india’,’in’) from dual;

REPLACE  REPLACE

----------- -----------

Xydia          dia

l) SOUNDEX

This will be used to find words that sound like other words, exclusively used in where clause.

Syntax: soundex (string)

Ex:

SQL> select * from emp where soundex(ename) = soundex('SMIT');

 EMPNO ENAME JOB MGR HIREDATE SAL DEPTNO -------- -------- ----- ----- ------------ --------- ---------- 7369 SMITH CLERK 7902 17-DEC-80 500 20

m) CONCAT

This will be used to combine two strings only.

Syntax: concat (string1, string2)

Ex:

SQL> select concat('computer',' operator') from dual;

CONCAT('COMPUTER'

-------------------------

computer operator

If you want to combine more than two strings you have to use concatenation operator (||).

SQL> select 'how' || ' are' || ' you' from dual;

'HOW'||'ARE

---------------

how are you

n) ASCII

This will return the decimal representation in the database character set of the first character of the string.

Syntax: ascii (string)

Ex:

SQL> select ascii('a'), ascii('apple') from dual;

ASCII('A') ASCII('APPLE')

------------ ------------------

97              97

o) CHR

This will return the character having the binary equivalent to the string in either the database character set or the national character set.

Syntax: chr (number)

Ex:

SQL> select chr(97) from dual;

CHR

-----

a

p) SUBSTR

This will be used to extract substrings.

Syntax: substr (string, start_chr_count [, no_of_chars])

Ex:

SQL> select substr('computer',2), substr('computer',2,5), substr('computer',3,7) from dual;

SUBSTR( SUBST SUBSTR

---------- -------  --------

omputer omput  mputer

Ø  If no_of_chars parameter is negative then it will display nothing.

Ø  If both parameters except string are null or zeros then it will display nothing.

Ø  If no_of_chars parameter is greater than the length of the string then it ignores and calculates based on the orginal string length.
Ø  If start_chr_count is negative then it will extract the substring from right end.

 1 2 3 4 5 6 7 8 C O M P U T E R -8 -7 -6 -5 -4 -3 -2 -1

q) INSTR

This will allows you for searching through a string for set of characters.

Syntax: instr (string, search_str [, start_chr_count [, occurrence] ])

Ex:

SQL> select instr('information','o',4,1), instr('information','o',4,2) from dual;

INSTR('INFORMATION','O',4,1) INSTR('INFORMATION','O',4,2)

------------------------------------ -------------------------------------

4                                                 10

Ø  If you are not specifying start_chr_count and occurrence then it will start search from the beginning and finds first occurrence only.

Ø  If both parameters start_chr_count and occurrence are null, it will display nothing.

r)  DECODE

Decode will act as value by value substitution.

For every value of field, it will checks for a match in a series of if/then tests.

Syntax: decode (value, if1, then1, if2, then2, ……. else);

Ex:

SQL> select sal, decode(sal,500,'Low',5000,'High','Medium') from emp;

 SAL DECODE ----- --------- 500 Low 2500 Medium 2000 Medium 3500 Medium 3000 Medium 5000 High 4000 Medium 5000 High 1800 Medium 1200 Medium 2000 Medium 2700 Medium 2200 Medium 3200 Medium

SQL> select decode(1,1,3), decode(1,2,3,4,4,6) from dual;

DECODE(1,1,3) DECODE(1,2,3,4,4,6)

 ----------------- ------------------------ 3 6

Ø  If the number of parameters are odd and different then decode will display nothing.

Ø  If the number of parameters are even and different then decode will display last value.
Ø  If all the parameters are null then decode will display nothing.

Ø  If all the parameters are zeros then decode will display zero.

s)  GREATEST

This will give the greatest string.

Syntax: greatest (strng1, string2, string3 … stringn)

Ex:

SQL> select greatest('a', 'b', 'c'), greatest('satish','srinu','saketh') from dual;

GREAT GREAT

------- -------

c            srinu

Ø  If all the parameters are nulls then it will display nothing.

Ø  If any of the parameters is null it will display nothing.

t)  LEAST

This will give the least string.

Syntax: greatest (strng1, string2, string3 … stringn)

Ex:

SQL> select least('a', 'b', 'c'), least('satish','srinu','saketh') from dual;

LEAST LEAST

------- -------

a           saketh

Ø  If all the parameters are nulls then it will display nothing.

Ø  If any of the parameters is null it will display nothing.

u)  COALESCE

This will gives the first non-null string.

Syntax: coalesce (strng1, string2, string3 … stringn)

Ex:

SQL> select coalesce('a','b','c'), coalesce(null,'a',null,'b') from dual;

COALESCE COALESCE

-----------  -----------

a                a

DATE FUNCTIONS

Ø  Sysdate

Ø  Current_date

Ø  Current_timestamp

Ø  Systimestamp

Ø  Localtimestamp

Ø  Dbtimezone

Ø  Sessiontimezone

Ø  To_char

Ø  To_date

Ø  Months_between

Ø  Next_day

Ø  Last_day

Ø  Extract

Ø  Greatest

Ø  Least

Ø  Round

Ø  Trunc

Ø  New_time

Ø  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.

This will add the specified months to the given date.

Ex:

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

----------------

11-JUN-90

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

---------------

11-AUG-89

Ø  If no_of_months is zero then it will display the same date.

Ø  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.

Ø  If the second parameter was null then it returns nothing.

Ø  If the you are not specifying the second parameter then round will resets the time to the begining of the current day in case of user specified date.

Ø  If the you are not specifying the second parameter then round will resets the time to the begining 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))

Ø  If the second parameter was year then it always returns the first day of the current year.

Ø  If the second parameter was month then it always returns the first day of the current month.
Ø  If the second parameter was day then it always returns the previous sunday.

Ø  If the second parameter was null then it returns nothing.

Ø  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

Ø  Uid

Ø  User

Ø  Vsize

Ø  Rank

Ø  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

Ø  Bin_to_num

Ø  Chartorowid

Ø  Rowidtochar

Ø  To_number

Ø  To_char

Ø  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

Ø  If all the bits are zero then it produces zero.

Ø  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.

GROUP FUNCTIONS

Ø  Sum

Ø  Avg

Ø  Max

Ø  Min

Ø  Count

Group functions will be applied on all the rows but produces single output.

a) SUM

This will give the sum of the values of the specified column.

Syntax: sum (column)

Ex:

SQL> select sum(sal) from emp;

SUM(SAL)

----------

38600

b) AVG

This will give the average of the values of the specified column.

Syntax: avg (column)

Ex:

SQL> select avg(sal) from emp;

AVG(SAL)

---------------

2757.14286

c) MAX

This will give the maximum of the values of the specified column.

Syntax: max (column)

Ex:

SQL> select max(sal) from emp;

MAX(SAL)

----------

5000

d) MIN

This will give the minimum of the values of the specified column.

Syntax: min (column)

Ex:

SQL> select min(sal) from emp;

MIN(SAL)

----------

500

e) COUNT

This will give the count of the values of the specified column.

Syntax: count (column)

Ex:

SQL> select count(sal),count(*) from emp;

 COUNT(SAL) COUNT(*) -------------- ------------ 14 14