MySQL将多行合并为一列

Question

I need to create an SQL statement to join multiple rows into one column. I have three table which are shown below. I need to join them all to get 1 row for each product (ie group by products.id).

There can be up to 6 images per product in the products_images table. I need a column for each image even if there are no product images.

Products Table
---
id
product_name
supplier_id


Suppliers Table
---
id
company_name


Product Images Table
---
id
product_id
fullsize

Here is an example dump of what i'm trying to achieve:

id  product_name   company_name  image1     image2     image3     image4     image5     image6
1   Ballpoint pen  Impression    img/1.jpg  img/2.jpg  img/3.jpg  img/4.jpg  img/5.jpg  null
2   T-shirt        Impression    img/6.jpg  img/7.jpg  img/8.jpg  null       null       null
3   Jumper         Impression    null       null       null       null       null       null

As you can see the first product has 5 images, second product has 3 and last product has 0 images.

How can I achieve the above result?

Thanks!

Answer 1

You need to look into using CASE statements.

For instance.

SELECT id,
 product_name,
 company_name,
 CASE WHEN Product Images Table.id = 1  THEN image1 ELSE NULL END AS image1,
 CASE WHEN Product Images Table.id = 2  THEN image1 ELSE NULL END AS image2
 ....
 FROM Products Table
 JOIN Suppliers Table
 JOIN Product Images Table