oracle create function syntax

The syntax for creating a function in Oracle is:

CREATE [OR REPLACE] FUNCTION function_name
    [(parameter_name [IN | OUT | IN OUT] data_type [, ...])]
RETURN return_data_type
IS
    [declaration_section]
BEGIN
    executable_section
    [EXCEPTION
        exception_section]
END [function_name];

Here is a brief explanation of each section:

- `CREATE [OR REPLACE] FUNCTION`: This is the SQL statement used to create a function. The `OR REPLACE` option allows you to modify an existing function instead of creating a new one.
- `function_name`: This is the name of the function you want to create.
- `parameter_name`: These are the input parameters for the function.
- `data_type`: This is the data type of the input parameters.
- `return_data_type`: This is the data type of the value returned by the function.
- `declaration_section`: This is an optional section where you can declare variables and constants used in the function.
- `executable_section`: This is the section where you write the code that executes when the function is called.
- `EXCEPTION`: This is an optional section where you can handle exceptions that occur in the function.
- `exception_section`: This is the section where you write the code to handle exceptions.

Note that the `IS` keyword separates the parameter and declaration sections from the executable section. The `END` keyword followed by the function name terminates the function definition.