•They provide a powerful tool for enhancing the basic query.
•A function can take zero or more arguments and return a single value.
•In Oracle SQL, there are two type of functions:
1.Single row function
2.Group functions

Single Row Function
•It works on individual columns from individual rows and returns one result per row.
•Arguments are in the form of a constant value, variable value, column and/or expression

Different types of single-row functions:

1.Character Functions
Takes a character string or character-type column as an argument and return a character or a numeric value.
2.Number Functions
Takes a number or number-type column as an argument and return a numeric value.
3.Date Functions
Takes a date value or date-type column as an argument and return a date-type data. (Exception: The MONTHS_BETWEEN function returns a numeric value.)
4.Conversion Functions
Convert value from one date-type to another.
5.General Functions

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