MySQL:aggiorna la query usando If else

Prova questa query

UPDATE tablename
SET col1=(CASE WHEN col1 LIKE 'A' THEN col1='IA' ELSE col1 END),
col2=(CASE WHEN col1 LIKE 'A' THEN col2='XXX' ELSE col2 END),
col3=(CASE WHEN col3 LIKE 'A' THEN col3='IA' ELSE col3 END),
col3=(CASE WEHN col3 LIKE 'A' THEN col4='XXX' ELSE col4 END)
WHERE
(col1='A' AND col2='UNKNOWN') OR (col3='A' AND col4='UNKNOWN')