Question

我是mysql的新手。这是我的db表的结构。*如何加入所有三个表来提供看起来像第四个表的结果？

表产品

id      name    category   user_id  
1       abc     2             1
2       syz     3             1

表类别

id      name
1       aaa
2       bbb
3       ccc

表product_image

id      image       product_id
1       abc.jpg         1
2       xyz.jpg         1

Forth表结果看起来像

id      name      category_name           image
 1      abc       aaa                    xyz.jpg

请帮我解决这个问题。我试过但没有得到正确的结果。

SELECT product. * , categories.name AS cat_name, product_image.image AS product_image
FROM `product`
INNER JOIN categories ON categories.id = product.category and `user_id`='1'
INNER JOIN `product_image` ON product_image.product_id = product.id
ORDER BY rand( )
LIMIT 1

编辑部分

我们需要来自product_image的一张图片，该图片根据product_id

关联多个图片

Answer 1

试试这个

SELECT p.id, p.name , c.name as category_name, i.image FROM Product AS p

INNER JOIN Categories as c

ON c.id=p.category LEFT JOIN 

(SELECT image, product_id FROM product_image ORDER BY RAND( ) LIMIT 1  ) AS i   ON i.product_id=p.id WHERE p.id=1

Answer 2

SELECT
    p.id, p.name, p.category, p.user_id,
    c.id, c.name as cat_name,
    prod_image.image as product_image
FROM
    Product p,
    Categories c,
    product_image prod_image
WHERE
    p.user_id=1
AND
    p.category=c.id
AND
    prod_image.product_id=p.id
ORDER BY rand() LIMIT 1

Answer 3

试试这个

SELECT product.name , categories.name AS cat_name, product_image.image AS product_image
FROM `product`
 JOIN categories ON (categories.id = product.category)
 JOIN `product_image` ON product_image.product_id = product.id Where product.`user_id`='1'
ORDER BY rand( )
LIMIT 1

Answer 4

SELECT Product.id as Id,Product.name  as name, Categories.name as category_name    ,product_image.image as image 
FROM 
Product, Categories,product_image
WHERE
Product.ID='1' AND Categories.Id='1' AND product_image='1'

sql连接查询问题有三个表

4 个答案: