Multiple Inner join blank result without error - mysql

Question

Hi dev's i'm new with "advanced" SQL I've try alone but I dont understand how to have the good result.
I'll try to take information from 4 tables in the same DB.
The first table items only have id and name.
2 others tables take the id from items to extract data.
The last tables takes one data from items_buy for print another data.
Lastly I concat 2 column from 2 DB for having a full information.
SELECT items.id, items.name, items_buy.item_cost AS item_cost, items_sales.item_price AS item_price, CONCAT(trader.name, planet.name) AS name_point
FROM ((((items
INNER JOIN items_buy ON items_buy.id = items.id)
INNER JOIN trader ON trader.id = items_buy.name_point)
INNER JOIN items_sales ON items_sales.id = items.id)
INNER JOIN planet ON planet.id = trader.planet)
WHERE items.id = 1;
I dont know how to make it work, she doesnt return an error in SQLyog or on my server.
In order:
ID / NAMEITEM / PRICE / SELLINGPRICE / NAME from concat
If you need more, some test data:
https://pastebin.com/6Bs4kbN9

Answer 1

I've run your test data and run your script against it. As I suggested in my commment, the problem is with the INNER JOIN you are using.
I am not sure whether you are aware, but when using an INNER JOIN, if the joined table is NULL for the current row, then nothing at all will be returned.
If you modify your query to use a LEFT JOIN, you will see the results that are available regardless of whether the joined tables are NULL or otherwise:
SELECT items.id, items.name, items_buy.item_cost AS item_cost, items_sales.item_price AS item_price, CONCAT(trader.name, planet.name) AS name_point
FROM ((((items
LEFT JOIN items_buy ON items_buy.id = items.id)
LEFT JOIN trader ON trader.id = items_buy.name_point)
LEFT JOIN items_sales ON items_sales.id = items.id)
LEFT JOIN planet ON planet.id = trader.planet)
WHERE items.id = 1;
This produces:
1 Agricium 24.45 25.6 NULL
1 Agricium 24.6 25.6 NULL
The problem in the case of your example is that the join to trader or planet has no result and therefore produces no output.