Select from related tables - mysql

Question

So in my data base i have 2 tables related:
The fields are id, name, price and a int so i know if they a all sold or not
fruits
|IDfruit| name | price | sold |
| 1 |orange | 5 | 0
| 2 |apple | 10 | 0
| 3 |grape | 15 | 1
| 4 |lemon | 7 | 1
primary key is IDfruit
images
|IDimage| url | idfruit_image
| 1 | image1.png | 1
| 2 | image2.png | 1
| 3 | image3.png | 2
| 4 | image4.png | 3
| 5 | image5.png | 4
| 6 | image6.png | 4
| 7 | image7.png | 4
IDimage is primary key and idfruit_image is a foreign key that references IDfruit
The result i want is all fruits and the FIRST image of each fruit.
So what i've done is
select fruits.*, url , idfruit_image
from fruits,images
where IDfruit = idfruit_image;
This return all fruits and all images of each fruit, but i would like just one image of each fruit, how can i achieve this?
And what if i want everything from all sold fruits and just the first image of each one

Answer 1

Use GROUP BY to get one row per fruit, and an aggregation function to select one of the images.
SELECT f.*, MAX(url) AS url
FROM fruits AS f
LEFT JOIN images AS i ON f.idfruit = i.idfruit_image
GROUP BY f.idfruit

Answer 2

I understand that you want the first image per fruit, first being defined as: the image with the smallest idimage.
If you just want the url of the image, a correlated subquery should be an acceptable solution:
select
f.*,
(
select i.url
from images i
where i.idfruit_image = f.idfruit
order by i.idimage
limit 1
) url
from fruits f
If you want the whole image record, one option is to join, then filter with a subquery:
select f.*, i.*
from fruits f
inner join images i on i.idimage = (
select min(i1.idimage) from images i1 where i1.idfruit_image = f.idfruit
)
Finally: in MySQL 8.0, you can use row_number() for this:
select *
from (
select
f.*,
i.*,
row_number() over(partition by i.idfruit_image order by i.idimage) as rn
from fruits f
inner join images i on i.idfruit_image = f.idfruit
) t
where rn = 1