Conditional expressions

Conditional expressions allow developers to control the action of the function based on a defined criteria. The following is an example of using a CASE statement to control how a string is treated based on its value. If the value is null, or contains a zero length string, it is treated the same as null.

CREATE OR REPLACE FUNCTION format_us_full_name(

                             prefix text, firstname text, 

                             mi text, lastname text, 

                             suffix text)

  RETURNS text AS

$$

DECLARE

  fname_mi text;

  fmi_lname text;

  prefix_fmil text;

  pfmil_suffix text;

BEGIN

  fname_mi := CONCAT_WS(' ',
                                  CASE trim(firstname) 

                                    WHEN '' 

                                    THEN NULL 

                                    ELSE firstname 

                                  END, 

                                  CASE trim(mi) 

                       ...