Sql在另一列的同一表中具有相同值的项目

Question

image of resource table

The above image is an image of a resource table of a site am building an android app for. Please sorry for my bad english and poor explanation, i will try to explain to the best i can. i have a table called resources as show below and it is part of another table called product. Product table is where the information about the product is stored while resource table is where images name and storage direction is stored. Each image has a seperate line. now if i try to run a query to link or join the product and resource table i start getting duplicated / repeated output values because of the images of the resources.

below is the product table

  pk_i_id | fk_i_user_id | p_name | p_description |  etc
    1       4              iphone     Iphone X  
    2       4              Cloth      Gucci     
    3       6              watch      Rolex Watch   
    4       3              car        Venza     
    5       7              tractor    CAT   
    6       9              Fruits     Melon     

below is the resource table

pk_i_id | fk_i_item_id | s_name | s_extension | s_content_type | s_path
    1     2             xDSDki0F    jpg         image/jpeg       oc-content/uploads/0/
    2     2             GAsk8vqW    jpg         image/jpeg       oc-content/uploads/0/
    3     3             D033Znu1    jpg         image/jpeg       oc-content/uploads/0/
    4     3             yZSPKeCj    jpg         image/jpeg       oc-content/uploads/0/
    5     5             rc8wCLOQ    jpg         image/jpeg       oc-content/uploads/0/
    6     5             tUWBh6vk    jpg         image/jpeg       oc-content/uploads/0/
    8     6             v3rSPl9s    jpg         image/jpeg       oc-content/uploads/0/
    9     7             8FTuKvgl    jpg         image/jpeg       oc-content/uploads/0/
    10    7             fzb2KzYq    jpg         image/jpeg       oc-content/uploads/0/
    11    7             9Qs7MgUl    jpg         image/jpeg       oc-content/uploads/0/
    12    8             3HmpjxC7    jpg         image/jpeg       oc-content/uploads/0/
    13    8             VF4M6PrE    jpg         image/jpeg       oc-content/uploads/0/
    14    8             tnIH7LqU    jpg         image/jpeg       oc-content/uploads/0/
    15    8             M5jKALrD    jpg         image/jpeg       oc-content/uploads/0/
    16    9             vBBSSfoD    jpg         image/jpeg       oc-content/uploads/0/

if i do a Query like this

select * products p, resource r where p.pk_i_id=r.fk_i_item_id

It will give me Multiple repeated Query due to multiple section of resource image storage. if Image about Car is 3 the query will display repeated query of car three times.

Judging from the above table if i try to fetch from here using this below Query"

select * from osoe_t_item_resource

it will display all those above table value in the app.

Please i need a query that will group the items with the same fk_i_item_id as another column example

instead of appearing like this output below

{"NewsApp":[
{"pk_i_id":"1","fk_i_item_id":"2","s_name":"xDSDki0F
{"pk_i_id":"2","fk_i_item_id":"2","s_name":"GAsk8vqW
{"pk_i_id":"3","fk_i_item_id":"3","s_name":"D033Znu1"},
{"pk_i_id":"4","fk_i_item_id":"3","s_name":"yZSPKeCj"},
{"pk_i_id":"5","fk_i_item_id":"5","s_name":"rc8wCLOQ"},
{"pk_i_id":"6","fk_i_item_id":"5","s_name":"tUWBh6vk"},
{"pk_i_id":"8","fk_i_item_id":"6","s_name":"v3rSPl9s"},
{"pk_i_id":"9","fk_i_item_id":"7","s_name":"8FTuKvgl"},
{"pk_i_id":"10","fk_i_item_id":"7","s_name":"fzb2KzYq"},
{"pk_i_id":"11","fk_i_item_id":"7","s_name":"9Qs7MgUl"},
{"pk_i_id":"12","fk_i_item_id":"8","s_name":"3HmpjxC7"},
{"pk_i_id":"13","fk_i_item_id":"8","s_name":"VF4M6PrE"},
{"pk_i_id":"14","fk_i_item_id":"8","s_name":"tnIH7LqU"},
{"pk_i_id":"15","fk_i_item_id":"8","s_name":"M5jKALrD"},
{"pk_i_id":"16","fk_i_item_id":"9","s_name":"vBBSSfoD"},
{"pk_i_id":"17","fk_i_item_id":"9","s_name":"kUt65zVb"},
{"pk_i_id":"18","fk_i_item_id":"9","s_name":"D5DXAszv"},

it should appear like this output

{"NewsApp":[
{"pk_i_id":"1","fk_i_item_id":"2","s_name":"xDSDki0F","s_name2":"GAsk8vqW"},
{"pk_i_id":"3","fk_i_item_id":"3","s_name":"D033Znu1","s_name2":"yZSPKeCj"},
{"pk_i_id":"5","fk_i_item_id":"5","s_name":"rc8wCLOQ","s_name2":"tUWBh6vk"},
{"pk_i_id":"8","fk_i_item_id":"6","s_name":"v3rSPl9s"},
{"pk_i_id":"9","fk_i_item_id":"7","s_name":"8FTuKvgl","s_name2":"fzb2KzYq","s_name3":"9Qs7MgUl"},
{"pk_i_id":"12","fk_i_item_id":"8","s_name":"3HmpjxC7"},
{"pk_i_id":"13","fk_i_item_id":"8","s_name":"VF4M6PrE","s_name2":"tnIH7LqU","s_name":"M5jKALrD"},
{"pk_i_id":"16","fk_i_item_id":"9","s_name2":"vBBSSfoD"},
{"pk_i_id":"17","fk_i_item_id":"9","s_name":"kUt65zVb","s_name2":"D5DXAszv"},

If you watch closely all times with the same id has be merged together in one out,

Please help me out.

Answer 1

I understant that, when there are records with the same fk_i_item_id , you want to keep only one, which has the lowest pk_i_id .

If you are using MySQL 8.0, this is straightforward with window function ROW_NUMBER() :

SELECT x.pk_i_id, x.fk_i_item_id, x.s_name
FROM (
    SELECT
        r.*, 
        ROW_NUMBER() OVER(PARTITION BY r.fk_i_item_id ORDER BY r.pk_i_id) rn
    FROM resource r
) x WHERE x.rn = 1

The inner query ranks each record within fk_i_item_id groups, and the outer query filters out duplicates.

---

If you are running an earlier version of MySQL, you can use a NOT EXIST condition with a correlated subquery that ensures that no other record exists with the same fk_i_item_id and a lower pk_i_id :

SELECT r.pk_i_id, r.fk_i_item_id, r.s_name
FROM resource r
WHERE NOT EXISTS (
    SELECT 1 
    FROM resource r1 
    WHERE r1.fk_i_item_id = r.fk_i_item_id AND r1.pk_i_id < r.pk_i_id
)