Definir activadores sobre la mesa:
CREATE TRIGGER lcase_insert BEFORE INSERT ON my_table FOR EACH ROW
SET NEW.language = LOWER(NEW.language);
CREATE TRIGGER lcase_update BEFORE UPDATE ON my_table FOR EACH ROW
SET NEW.language = LOWER(NEW.language);
Luego actualice los datos existentes:
UPDATE my_table SET language = LOWER(language);