Mysql with join statement - mysql

Question

I have the following tables
1) discounts
+--------------------------------------------+
| ID discount_description discount_type |
+--------------------------------------------+
| 17 20% off PERCENT |
| 19 Citric ABSOLUTE |
+--------------------------------------------+
Table 2 - Products Included
+------+--------------+------------------+
| ID | discount_id | product_id |
+------+--------------+------------------+
| 2 | 17 | 52238403 |
| 3 | 17 | 52238409 |
| 4 | 19 | 52238408 |
+------+--------------+------------------+
Table 3 - Products Excluded
+---------------------------------+---------------+
| ID discount_id | product_id |
+---------------------------------+---------------+
| 2 17 | 52238411 |
| 3 17 | 52238408 |
+---------------------------------+---------------+
I need the query to fetch all the discounts based on product ID's from included table and excluded table. And it should also include the rows from discounts which is not present in products included/excluded table.
Below is a sample one to fetch discounts based on products 52238408,52238403.
SELECT
discounts.id as ID1,
discount_products.product_id as p1,
exclude_discount_products.product_id as p2
FROM discounts
LEFT JOIN `discount_products` ON 1=1
AND discounts.id = discount_products.discount_id
LEFT JOIN `exclude_discount_products` ON 1=1
AND discounts.id = exclude_discount_products.discount_id
WHERE discount_products.product_id IN (52238408,52238403)
AND exclude_discount_products.product_id NOT IN (52238408,52238403)
The query is just a basic version and i am pretty sure it's incorrect. But basically i wanted to check both the tables for product ID.
I am suppose to get discount 19 as the output since products excluded has 52238408, So 17 should ignored. But it gives 17 instead. Not sure what i am missing, any help is much appreciated.
Thanks

Answer 1

Not sure if you want this you didnt include the expected output.
Create table/insert data
CREATE TABLE discounts
(`ID` INT, `discount_description` VARCHAR(7), `discount_type` VARCHAR(8))
;
INSERT INTO discounts
(`ID`, `discount_description`, `discount_type`)
VALUES
(17, '20% off', 'PERCENT'),
(19, 'Citric', 'ABSOLUTE')
;
CREATE TABLE discount_products
(`ID` INT, `discount_id` INT, `product_id` INT)
;
INSERT INTO discount_products
(`ID`, `discount_id`, `product_id`)
VALUES
(2, 17, 52238403),
(3, 17, 52238409),
(4, 19, 52238408)
;
CREATE TABLE exclude_discount_products
(`ID` INT, `discount_id` INT, `product_id` INT)
;
INSERT INTO exclude_discount_products
(`ID`, `discount_id`, `product_id`)
VALUES
(2, 17, 52238411),
(3, 17, 52238408)
;
Query
SELECT
discounts.id AS ID1
, product_id AS p1
, (
# SELECT matching product_id FROM exclude_discount_products based on product_id (checks excludes)
SELECT
product_id
FROM
exclude_discount_products
WHERE
product_id = discount_products_NOT_IN_exclude_discount_products.product_id
)
AS p2
FROM (
# SELECT all discount_products that dont have the same discount_id, product_id as in exclude_discount_products
SELECT
*
FROM
discount_products
WHERE (
discount_id
, product_id
)
NOT IN (
SELECT
discount_id
, product_id
FROM
exclude_discount_products
)
)
AS
discount_products_NOT_IN_exclude_discount_products
INNER JOIN
discounts
ON
discount_products_NOT_IN_exclude_discount_products.discount_id = discounts.id
WHERE
product_id IN(
52238408
, 52238403
)
Result
ID1 p1 p2
------ -------- ----------
17 52238403 (NULL)
19 52238408 52238408