我试着数一数儿童电影和非儿童电影。这就是我目前所知道的。
这是为了显示表格，其中是和否，是为儿童电影的pg和g

select 
    category.name,film.title,film.rating,
    if(
        category.name='For_Kids' 
        or film.rating='PG' 
        or film.rating='G' ,"YES","NO" 
    ) 'rating yes or no' 
from
    film 
    inner join film_category on film.film_id = film_category.film_id 
    inner join
    category on film_category.category_id =category.category_id 
order by film.title asc;

我试着数数儿童电影，但除了儿童电影外，我一直在数数其他电影。这就是我目前所知道的。

select 
    sum(if(film.rating='G'or film.rating='PG',1,0)) as totalkidsfilms 
from
    film 
    inner join film_category on film.film_id = film_category.film_id
    inner join category on film_category.category_id =category.category_id
order by film.title asc;