SQL functions are divided into 2 categories as follows:
- Single row function
- Group function
1. Single row function :
Single row function will take single input and gives a single output.
Ø Single row functions are divided into five categories:
ü Number function (arithmetic functions) :
These functions are used to process the numbers
v Numeric function are as fallows:
- Abs: Will return the absolute (unsigned) value.
For this function a single parameter is required.
Syntax:ABS (NUMBER)
Ex: Select abs (2), abs (-2), abs (0), abs (null) from dual
Output: 2 2 0 ___
- Sign: Will give the sign of the given number
( 0(zero), 1(positive), -1(negative) ).
For this function a single parameter is required.
Syntax: SIGN (NUMBER)
Ex: Select sign (100) from dual
Output: (+) 1
- Sqrt: Will give the square root of the given value.
(In this value must be positive)
For this function a single parameter is required.
Syntax: SQRT (NUMBER)
Ex: Select sqrt (81) from dual
Output: 9
- Mod: will give the reminder.
For this function two parameters are required.
And in this the first value is divided by the next value.
Syntax: MOD (VALUE, DIVISOR)
Ex: Select mod (8, 3) from dual
Output: 2
- Nvl: will substitute the given value in the place of null value of the given
Column
For this function two parameters are required.
One is substitute value and column name.
Syntax: NVL (COL, SUBSTITUTE VALUE)
Ex: Select nvl (comm., 100) from EMP
Output: 100
- Power: This will give the power value
For this function two parameters are required (Value, power)
Syntax: POWER (VALUE, EXPONENT (POWER))
Ex: select power (5, 5) from dual
Output: 3125
- Ceil: will give the whole number that is greater than or equal to the
Specified value
For this function a single parameter is required.
Syntax: CIEL (VALUE)
Ex: select ceil (months_between (sysdate, hiredate)/12) as exp from EMP
Output: 31 (30.1332226666)
- Floor: will give the whole number that is less than or equal to the
Specified value
For this function a single parameter is required.
Syntax: FLOOR (VALUE)
Ex: select floor (sal /31) as Asal from EMP
Output: 84(84.5806451)
- Round: This function will round the given number to the specified
Places
For this function two parameters are required
Syntax: ROUND (VALUE, PRECISION)
- In this function if the second (PRECISION ) value is positive then
Then it gives number of places after decimal
Ex: select round ((sal/31), 2) as d sal from EMP
Output: 84.58(84.580645161)
- If the precision value is negative then it will round up the given value
-1 then it round up to the nearest tens.
-2 then it round up to the nearest hundreds.
-3 then it round up to the nearest thousands.
And so on.
Ex: select round ((sal/31),-2) from EMP
Output: 100(84.580645161)
- Trunc: This will truncate (just remove) the specified precision / places
For this function two parameters are required
Syntax: TRUNC (VALUE, PRECISION)
- In this function if the second (precision ) value is positive then
Then it gives number of places after decimal
Ex: select trunc (sal*40/100+88.123, 2) as hra from EMP
Output: 1136.92(1136.923)
- If the specification value is negative then it will truncate the given value up to specified places ( it just replace with 0(zero))
Ex: select trunc (sal*12,-2) as Asal from EMP
Output: 31400 (31464)
- Greatest: This function will give the greatest value in the given values
This function accepts any number of parameter
Syntax: GRETEST (VALUE1, VALUE2, VALUE3, VALUE4 ….VALUEN)
Ex: select greatest (12,21,45,54,34,46,7,45,65,99,99) from dual
Output: 99
Or
Select greatest (-12,-21,-45,-54,-34,-46,-7,-45,-65,-99,-99) from dual
Output: -7
- Least: This function will give the least(smallest) value in the given
Values
This function accepts any number of parameter
Syntax: LEAST (VALUE1, VALUE2, VALUE3, VALUE4 ….VALUEN)
Ex: select least (12,21,45,54,34,46,7,45,65,99,99) from dual
Output: 7
Or
Select least (-12,-21,-45,-54,-34,-46,-7,-45,-65,-99,-99) from dual
Output: -99
- Coalesce: This function will return the first not null value
This function accepts any number of parameter
Syntax: COALESCE (VALUE1, VALUE2, VALUE3, VALUE4 ….VALUEN)
Ex: select coalesce(1,2,3,4,5,6), coalesce(null,null,8,null) from dual
Output: 1 8
- NVL2: This function will returns the 2nd value if the 1st value is not null
Or it will return the 3rdvalue if the 1st value is null.
This function requires three parameters
NVL2 (VALUE1, VALUE2, VALUE3)
Ex: select nvl2 (com, sal, empno) from EMP
Output: 7839 (where comm. Is null)
ü Character function (string manipulation function) :
These functions will process the character or (strings).
- Character functions are divided as fallows:
1. Initcap: This function will capitalize the first letter in the given strings
SYNTAX: INITCAP (STRING)
Ex: select initcap (ename) from EMP
Output: King
2. Upper: This function will convert the string into uppercase
SYNTAX: UPPER (STRING)
Ex: select upper (ename) from EMP
Output: KING
3. Lower: Will convert the string into lowercase
SYNTAX: LOWER (STRING)
Ex: select lower (ename) from EMP
Output: king
4. Length: will give the length(the space used in terms of number ) of the given string
SYNTAX: LENGTH (STRING)
Ex: select length (dname) from dept
Output: 14
5. ASCII: will return the (ASCII code) decimal representation in the database character set .of the first character of the string.
The standard numbers are as fallows:
a to z = 65 to 90, A to Z = 97to 122, and 0 to 9 = 48 to 97
SYNTAX: ASCII (STRING)
Ex: select ASCII (ename) from EMP
Output: 75 (of k)
6. Chr: This function will returns the ascii character to the given ascii code(number)
SYNTAX: CHR (NUMBER)
Ex: select Chr (97) from dual
Output: a
7. Substr: This will return the specified substring from the given string
This function requires 3 parameters to process.
SYNTAX: SUBSTR (STRING, START_CHR_COUNT, NUM_OF_CHR)
EX: select substr(‘computer’,3),substr(‘computer’,3,5), substr(‘computer’,3,7)from emp Output: mputer mput mputer
8. Instr:This function will helps us to search set of characters through a string
SYNTAX: INSTR (STRING, SEARCH STRING, START_CHR_COUNT,
OCCURRENCE)
EX: SELECT INSTR (‘IRONMAN3’,’R’, 1, 2) FROM DUAL
Output: 7
9. Lpad: will allow padding the left side column with any set of characters.
It means it fills the blank spaces with the specified set of characters to the left side column up to specified length.
SYNTAX: LPAD (STRING, LENGTH, PADDING CHAR)
Ex: select lpad (sal, 10,’>’) from EMP
Output: >>>>>>2622
10. Rpad: will allow us padding the right side column with any set of characters. that is it fills the blank spaces with the specified set of
Characters to the right side column up to specified length
SYNTAX: RPAD (STRING, LENGTH, PADDING CHAR)
Ex: select rpad (sal, 10,’<’) from EMP
Output: 2622<<<<<<
11. Ltrim: This function will trim (remove) the specified character from extreme left side of the given string.
By default second parameter is a blank space.
SYNTAX: LTRIM (STRING, UNWANTED CHARACTER STRING)
Ex: select ltrim (‘King’,’K’) from dual
Output: ing
12. Rtrim: This function will trim (remove) the specified character from extreme right side of the given string.
By default second parameter is a blank space.
SYNTAX: RTRIM (STRING, UNWANTED CHARACTER STRING)
Ex: select rtrim (computersss,’s’) from dual
Output: computer
13.Concat: This function is used to join two strings
SYNTAX: CONCAT (STRING1, STRING2)
Ex: select concat (‘HAPPY’, ‘NEW YEAR’) from dual
Output: HAPPY NEWYEAR
14. Translate: This function will replace the set of characters , character by character
SYNTAX: TRANSLATE (STRING, OLD CHR, NEW CHR)
EX: select translate (sal, ‘1234’, abcd) from EMP
Output: b6bb
15. Replace: This function will replace the set of characters, string by string (the whole string will be replaced)
SYNTAX: REPLACE (STRING, OLD STR, NEW STR)
EX: select replace ( ‘NARAYANMURTI’,’INDIA’,’MURTI’) from dual
Output: INDIAMURTI
16. Decode: This function will help to substitute value by value
Syntax: decode (value (column name), if1, then1, if2, then2…..else)
Ex: select decode (sal, (<1000), low, (>4000), high, medium) from EMP
Output: low high, (for other numbers) medium
17. Soundex: This is used to find words that sound like other words, exclusively used in where clause
Syntax: soundex (string)
Ex: select * from EMP
Where soundex (ename) = soundex (‘FORD’)
Output: 7928 ford. Anylist, 7566, 12-03-1981, 1300, __, 20
ü Date function:
These functions are used to process the dates.
Oracle default date format is (DD-MM-YY)
We can change the format when required.
v Date functions are divided as fallows:
- SYDSDATE: This function is used to access the current date and time
Ex: Select sysdate from dual
Output: 1/4/2012 2:49:42 PM
- Current date: This will give the current date in the session’s time zone.
Ex: select current date from dual;
Output: 1/4/2012 2:50:53 PM
- Months_betweeen: This function will give the number of months between the 2 dates given.
Syntax: months_between (date1 (recent), date2 (old))
Ex: Select months_between (sysdate, hiredate) from EMP
Output: 361.600641054361
- Add _months: This is used to add number of months to an given date
Syntax: add_months (date, number)
Ex: select add_months (hiredate, 5) from EMP
Output: 4/17/1982
- Last_day: This function is used to get the last day of the given month
Syntax: Last_day (date)
Ex: select last_day (sysdate) from EMP
Output: 1/31/2012 2:54:55 PM
- Next_day: This function is used get the date of a given day after the given date
Syntax: Next_day (date,’ day’)
Ex: select next_day (hiredate,’sunday’) from EMP
Output: 11/22/1981
Data conversion function:
These functions are used to convert the data from one format to other format.
1 To_char:
This function is used to convert the number or date to character format
Syntax: to_char (number / date, format)
Ex: select to_char (hiredate, ‘day’) from EMP
Output: Tuesday
2. To_number:
This function is used to convert the character or string into number format
Syntax: TO_ number (char, format)
Ex: select to_number (‘1, 23,456’,’99, 99,999’) from dual
Output: 123456
- To_date:
This function is used convert the given character string into date format
Syntax: To_Date (char, format)
Ex: select to_date (’12-jan-2011’) from EMP
Output: 1/12/2011
- Group Function:
Here in this Group function it set (group) of input and Gives a single out put
Fallowing are the group functions:
1) Max: It is used to get the max value in the given (column)set of values
Syntax: max (column name)
Ex: select max (sal) from EMP
Output: 5000
2) Min: it is used to get the min value in the given (column)set of values
Syntax: min (column name)
Ex: select min (hiredate) from EMP
Output: 2/20/1981
3) Avg: it is used to get the average value of the given (column ) set of values and (it ignores the null value )
Syntax: avg (column name)
Ex: select avg (sal) from EMP
Output: 2882.85714285714
4) Sum: it is used to get the total of the given ( column ) set of values
Syntax: Sum (column name)
Ex: select sum (sal) from EMP
Output: 40360
5) Count: it is used to count the number of rows in the given set of values
Syntax: count (column name)
Ex: select count (comm) from EMP
Output: 4
No comments:
Post a Comment