Create a simple function : Function « Function Procedure Packages « Oracle PL/SQL Tutorial

SQL> create or replace FUNCTION iifn(boolean_expression in BOOLEAN,
  2                true_number IN NUMBER,
  3                false_number IN NUMBER)
  4  RETURN NUMBER IS
  5  BEGIN
  6    IF boolean_expression THEN
  7      RETURN true_number;
  8    ELSIF NOT boolean_expression THEN
  9      RETURN false_number;
 10    ELSE
 11      --nulls propagate, i.e. null input yields null output.
 12      RETURN NULL;
 13    END IF;
 14  END;
 15  /

Function created.

27.1.Function
	27.1.1.	Functions
	27.1.2.	Describe a user-defined function
	27.1.3.	create or replace FUNCTION iifn(boolean_expression in BOOLEAN,true_number IN NUMBER,false_number IN NUMBER)
	27.1.4.	Storing PL/SQL function in the Database
	27.1.5.	Create a simple function
	27.1.6.	Creating a Function to deal with business rules
	27.1.7.	CREATE OR REPLACE a function
	27.1.8.	Calling a Function
	27.1.9.	Calling a Function for a table
	27.1.10.	Function without parameters
	27.1.11.	Exit a function
	27.1.12.	How to Call a Function from PL/SQL With or Without Parameters
	27.1.13.	Local Subprograms
	27.1.14.	Dependency Example
	27.1.15.	The FullName Function
	27.1.16.	PLW-05005: function NO_RETURN returns without value at line 21
	27.1.17.	Use function to check passwords