how to create query for below table [duplicate] - mysql

Question

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Is storing a delimited list in a database column really that bad?
(10 answers)
Closed 3 years ago.
This is the table of database
**
id products free_pro_id
1 laptop 2
2 pen-drive -
3 hard-disk 2,4
4 mouse 3
i am just wondering how to create query for below output
product free_id_pro**
laptop pen-drive
hard-disk pen-drive,mouse
mouse hard-disk

Answer 1

I understand your problem. But your table implementation is not correct.
First, you have to learn about Database Normalization.
Please refer to this link
https://www.studytonight.com/dbms/database-normalization.php
You can have a table for products and another table for promotions.
Table Products
In this table you can have the prodId and the prodName
prodId-------prodName
1--------------laptop
2--------------pen_drive
3--------------hard_disk
4--------------mouse
Table Promotion
In this table, you can store what are the free products you are giving when user buys a product.
promoId--prodId----freeProdId
1-------------1------------2
2-------------3------------2
3-------------3------------4
4-------------4------------3
If you want to get the free products given for laptop you can do the following query
SELECT freeProdId from Promotion where prodId = 1;
I have given a very simple query to give you a basic understanding. You can modify the query, play around with it and do many things. (Ex. Get the prodName instead of the id)

Answer 2

This is the table of database arrange this type of product table in database
id ----- products ----- free_pro_id
1 ------- laptop --------- 2
2 ------- pen-drive-------- -
3 ------ hard-disk ------- 2
3 ------ hard-disk ------- 4
4 ------- mouse ---------- 3
This is the query to get output of above table
SELECT foo.products ,product.products FROM product foo inner join product on foo.id=product.free_pro_id