具有多个联接的多个mysql表

Question

I have 4 mysql tables as follows:

products:
----------------------------------------------------
product_id    product_name   price    discount
----------------------------------------------------
1             product 1      10.00       1.00
2             product 2      20.00       2.00
3             product 3      25.00       1.00
----------------------------------------------------

subcategory

----------------------------------------------------
cb_category_id    subcategory_name       status
----------------------------------------------------
   1                 subcat 1            Enabled
   2                 subcat 2            Disabled
   3                 subcat 3            Enabled
------------------------------------------------------

temp_products
------------------------------------------------------
id               productid               catid
------------------------------------------------------
1                   1                      1
2                   1                      2
3                   2                      1
------------------------------------------------------

product_images
------------------------------------------------------
product_id                images
------------------------------------------------------
   1                    image1.jpg
   1                    image2.jpg
   2                    image2-1.jpg
--------------------------------------------------------

temp_products.catid and subcategory.cb_category_id

and

temp_products.productid and products.product_id

and

products.product_id and product_images.product_id

are related..A product can have multiple images.

I wish to have a subcategory selected with all products with first image for a product from product_images and WHERE subcategory.status is "Enabled"...?? Need to limit output to only 1 cb_category_id with multiple product_id under it, like as follows:

----------------------------------------------------------------------------------
cb_category_id   subcategory_name product_id  product_name, price, discount, images
-----------------------------------------------------------------------------------
     1              subcat 1           1        product 1    10.00   1.00    image1.jpg
     1              subcat 1           2        product 2    20.00   2.00    image2- 1.jpg

My query is as follows:

SELECT p.product_id,p.product_name,p.price,p.discount,s.cb_category_id,s.subcategory_name 
FROM products p,subcategory s
INNER JOIN temp_products ON p.product_id = temp_products.productid
INNER JOIN temp_products tp ON tp.catid = s.cb_category_id
WHERE tp.catid = s.cb_category_id        

I am getting unknown column p.product_id in on clause ....Regarding including images i am at a dead end. Help requested...I am unable to comprehend the joins required for the same...

Answer 1

you have a typo . you dont have products_id in your products table.

change this

  p.products_id

to

  p.product_id

EDIT: rewrite your query like that :

  SELECT  p.product_id,p.product_name,p.price,p.discount,s.cb_category_id,s.subcategory_name ,pi.images
  FROM products p
  INNER JOIN temp_products tp ON p.product_id = tp.productid
  INNER JOIN product_images pi ON p.product_id = pi.product_id
  INNER JOIN subcategory s ON tp.catid = s.cb_category_id
  GROUP BY p.product_id 

Answer 2

Your 'temp_products' table is basically a mapping table for 'products' and 'subcategory' . I have not tested the following code but you'll get the idea from comments(text after # character). this should solve your problem:

SELECT p.product_id,p.product_name,p.price,p.discount,s.cb_category_id,s.subcategory_name,pim.images
FROM products p
INNER JOIN temp_products tp ON p.product_id = tp.productid          #remove duplicate join
INNER JOIN subcategory s ON tp.catid = s.cb_category_id
LEFT JOIN product_images pim ON pim.product_id =p.product_id        #join for images
WHERE s.status = 'Enabled' AND                                      #subcategory is enabled
s.cb_category_id = '1'                                              #subcategory you want to be selected
GROUP BY p.product_id ORDER BY p.product_id, pim.images;