Aggregate Functions

• AVG() – Returns the average value
• COUNT() – Returns the number of rows
• FIRST() – Returns the first value
• LAST() – Returns the last value
• MAX() – Returns the largest value
• MIN() – Returns the smallest value
• SUM() – Returns the sum
• STDDEV – Returns standard deviation of column
• VARIANCE – Returns the variance of N.

Character Functions 

• LOWER – Converts alpha characters values to lowercase.
• UPPER  – Converts alpha characters values to uppercase.
• CONCAT – Concatenates the first character value to the second character value.
• SUBSTR – Returns specified characters from character value, string from a specified position m to n charaters long.
• LENGTH – Returns the number of characters in a value.
• INSTR – Returs the numaric position of a named character.
• INITCAP – Returns a string with the first letter of each word in upper case, keeping all othered.
• LPAD – Pads the character value right- specified to a total width of n character positions.
• RPAD – Pads the character value left – specified to total width of n character positions.
• TRIM – Trims heading or tailing charecters ( or both) from a specified string.
• LTRIM – It enables to trim heading characters from a character string.
• RTRIM – It enables to trim tailing characters from a character string.
• REPLACE – Returns the every occurences of search string replace by the the replacement string.
• TRANSLATE – Used to translate character by character in a string.
• CHAR – Returns a character having the binary equivalent to n.
• ASCII – Returns the decimalrepresentation in the character database set of the first character of the char.

Number Functions :

• ROUND – Returns the m round to n places right from the decimal part.
• TRUNC – Returns m truncated to n decimal places.
• CEIL – Returns the largest integer greater than or equal to n.
• FLOOR – Returns the smallest integer less than or equal to n.
• MOD – Returns reminder of m divided by n
• POWER – Returns m raised to the nth power.
• SQRT – Returns square  root of n as real value.
• ABS – Returns the absolute value of n.
• SIGN – Returns the sign.

Miscellaneous Functions :

• GREATEST – Used to pick highest values form the list of values.
• LEAST – Used to pick lowest value from the list of values.
• USER – Returns the current oracle users names with in the VARCHAR2 data type.
• UID – It gives a number that identified the user since oracle is used in a multi-user environment.
• USERENV – Returns information of varchar2 data type avove the current session.
• VSIZE – Returns the number of bytes in the internal representaion of Expr.
• SOUNDEX – Returns a character string containing the representaion of CHAR.