select p.name as p_name,
c.name as c_name,
b.name as b_name,
price1,
model
from product as p,product_category as c,brand as b
where p.categoryid=c.id
and p.brandid=b.id
and c.id=
615432733113008653
and b.id=
-9014347894162505346
order
by p.name;
問題描述：發現商品id=-9223342254556101702的id存在錯誤，查詢該品牌的其他商品id是否存在問題。分為兩步：找到商品id=-9223342254556101702對應的品牌id,再由品牌id確定該品牌的所有商品id。即用子查詢解決。
select brandid
from product
where product.id=
-9223342254556101702
;
select product.id,product.name
from product
where product.brandid=
4860751648763693994
;
select product.id,product.name
from product
where product.brandid=
(select brandid
from product
where product.id=
-9223342254556101702
);
select p1.id,p1.name
from product as p1,product as p2
where p1.brandid=p2.brandid #自聯結
and p2.id=
-9223342254556101702
;
select c.*,
p.name as p_name,
b.name as b_name,
price1,
model
from product as p,product_category as c,brand as b
where p.categoryid=c.id
and p.brandid=b.id
and c.id=
615432733113008653
and b.id=
-9014347894162505346
limit0,
5;
下面是外部右聯結
select product.name as p_name,
product_category.name as c_name
from product right
outer
join product_category
on product.categoryid=product_category.id
limit0,
5;
下面是外部左聯結
select product.name as p_name,
product_category.name as c_name
from product left
outer
join product_category
on product.categoryid=product_category.id
limit0,
5;
下面是內部聯結：包含有關聯行
select product.name as p_name,
product_category.name as c_name
from product inner
join product_category
on product.categoryid=product_category.id
limit0,
5;
select product.name as p_name,
product_category.name as c_name,
count
(product.id)
as num_product
from product inner
join product_category
on product.categoryid=product_category.id
group
by c_name;
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