ORACLE SQL Merge : insert or update key value pair

sql_merge_stmt.sql

--create table configuration(key varchar(50), val varchar(100));

merge INTO configuration t USING --- table name configuration
(SELECT 
     substr(keyVal,1, instr(keyVal,'=')-1) key
   , substr(keyVal,instr(keyVal,'=')+1) val
  ----- add other columns
  from (select 'key=val' keyVal FROM dual) d  ------- replace key=val
 
) s ON ( s.key = t.key )
WHEN matched THEN
  UPDATE
  SET t.val            = s.val 
  ----- add other columns
  WHERE t.val         <> s.val WHEN NOT matched THEN
  INSERT VALUES
    (
      s.key
      , s.val
  ----- add other columns
    )
;