MySQL Unique Exemption Case with Group By - mysql

Question

I have a set of data that lists when a User changes a Product, we look at who changed it, when, the old cost and new cost, and the percentage price difference.
I want to use a group by, where statement, or case to group by and exclude products that filters out changes were the change occurred in the same day and resulted in the original price staying.
So the situation I want to exclude would look like this:
| product | Changed By | Old Price | New Price | % diff | Day Changed |
|----------|------------|-----------|-----------|--------|-------------|
| blue hat | me | 94.00 | 95.00 | 1.05 | 2016-11-28 |
| blue hat | me | 95.00 | 94.00 | 1.05 | 2016-11-28 |
Any ideas how to do this with MySql?

Answer 1

Here is a working version for anyone who wants to see this done using subqueries, where's, and group by's.
This query looks at the changes to an Item's cost by a User for the span of 1 day, where it pulls in all the results from "yesterday". It lists all the changes for that day one asc and one desc and compares the price changes that way. If they are the same from the oldest change to the newest change of that say then it is exempted.
SELECT
us.Name,
it.Name,
pal.CS_PA_Line_Supplier__c as supplier_name,
newest.NewValue as new_value,
oldest.OldValue as old_value,
((newest.NewValue - oldest.OldValue) / oldest.OldValue) * 100 as Percentage
FROM
(
SELECT Id, Name, KNDY4__Item__c, CS_PA_Line_Supplier__c
FROM KNDY4__Contract_Line__c
) pal
LEFT JOIN
(
SELECT *
FROM
(
SELECT
ParentId,
CreatedById,
CreatedDate,
Field,
NewValue
FROM KNDY4__Contract_Line__History
WHERE CreatedDate >= CURDATE() - INTERVAL 1 DAY
AND CreatedDate < CURDATE()
AND Field='KNDY4__Negotiated_Price__c'
ORDER BY CreatedDate DESC
) cd
GROUP BY ParentId
) newest
ON newest.ParentId=pal.Id
LEFT JOIN
(
SELECT * FROM (
SELECT
ParentId,
OldValue
FROM KNDY4__Contract_Line__History
WHERE CreatedDate >= CURDATE() - INTERVAL 1 DAY
AND CreatedDate < CURDATE()
AND Field='KNDY4__Negotiated_Price__c'
ORDER BY CreatedDate ASC
) cd
GROUP BY ParentId
) oldest
ON oldest.ParentId=pal.Id
LEFT JOIN
(
SELECT Id, Name
FROM User
) us
ON us.Id = newest.CreatedById
LEFT JOIN
(
SELECT Id,Name
FROM KNDY4__Item__c
) it
ON it.Id=pal.KNDY4__Item__c
WHERE newest.ParentId IS NOT NULL
AND oldest.OldValue IS NOT NULL
AND newest.NewValue != oldest.OldValue
GROUP BY pal.KNDY4__Item__c, pal.CS_PA_Line_Supplier__c
ORDER BY it.Name ASC