DELIMITER $$
CREATE TRIGGER Pc_Auditoria
AFTER UPDATE ON pcTotal
FOR EACH ROW
INSERT INTO auditoria (pc, personaAnterior, horario, persona, fecha_mod)
VALUES (NEW.pc, OLD.persona, NEW.horario, NEW.persona, NOW());
DELIMITER ;

DELIMITER $$
CREATE TRIGGER Pc_Auditoria AFTER UPDATE ON pcTotal
FOR EACH ROW
BEGIN
    IF <tu condición aca> THEN BEGIN
        INSERT INTO auditoria (pc, personaAnterior, horario, persona, fecha_mod)
        VALUES (NEW.pc, OLD.persona, NEW.horario, NEW.persona, NOW());
    END; END IF;
END$$
DELIMITER ;

IF NEW.persona IS NOT NULL THEN

DELIMITER $$
CREATE TRIGGER Pc_Auditoria BEFORE UPDATE ON pcTotal
FOR EACH ROW
BEGIN
    IF COALESCE(NEW.coordinador, '') != '' THEN BEGIN
        INSERT INTO auditoria (pc, personaAnterior, horario, persona, fecha_mod)
        VALUES (NEW.pc, OLD.persona, NEW.horario, NEW.persona, NOW());
    END; END IF;
END$$
DELIMITER ;