SQL-Einfügung in der ersten leeren Spalte in einer Zeile MySQL-Fehler

Verwenden Sie update

$sql="update TABLENAME set 
GAME1 = case when GAME1 = '' then $item3 else GAME1 end,
GAME2 = case when GAME2 = '' and GAME1 <> '' then $item3 else GAME2 end,
GAME3 = case when GAME3 = '' and GAME1 <> ''and GAME2 <> '' then $item3 else GAME3 end
WHERE ID = 89 ";