加入3个表多对多关系单个查询

Question

How can I write one MYSQL query for the following

I have 3 tables

I know the logged in user_id is 25

Users(id,first_name,last_name) ,

userproduducts(user_id,product_id) ,

Product(id,title,description,price)

userproducts is a many to many resolved table

how can I write a query that will get me the first_name , last_name of the user with id=25 and get everything in the product table of products where user_id = 25 in userproducts table??

thank you

Answer 1

A simple straightforward JOIN will give you what you want:

SELECT 
  u.first_name,
  u.last_name,
  p.*
FROM users              As u
INNER JOIN userproducts AS up ON up.user_id     = u.id
INNER JOIN product      AS  p ON up.product_id  = p.id
WHERE u.id = 25;

Answer 2

This is done with two joins. They should be LEFT JOINS if you want to get the users who do not have products.

SELECT u.first_name, u.last_name, p.*
FROM users u
LEFT JOIN userproducts up ON u.id = up.user_id
LEFT JOIN product on up.product_id = p.id
WHERE p.id = 25

The product information will be null in the case where there are no products. If you don't want the null products, use the INNER JOIN, also just written as JOIN that is found in the previous answers.

SELECT u.first_name, u.last_name, p.*
FROM users u
JOIN userproducts up ON u.id = up.user_id
JOIN product on up.product_id = p.id
WHERE p.id = 25

Answer 3

try this

SELECT 
 ut.first_name,
 ut.last_name,
 pt.*
FROM users              As ut
INNER JOIN userproducts AS upro ON upro.user_id     = ut.id
INNER JOIN product      AS  pt ON upro.product_id = pt.id
WHERE ut.id = 25;