SQL Join Query - returning duplicates - need distinct values only

Here is my query

SELECT DISTINCT c.PartNumber, SP.SerialNumber, SP.MAC
    FROM Order C
    INNER Join SO_MAC SP
    ON C.SO = SP.SO
    Where c.SO='847403'

The problem is there are only 30 SerialNumber & MAC addresses and it's returning 60 for this current query.

The SO (Sales Order) has 2 line items - so I think it has something to do with that....if I change it to this (LI = LineItem)...Then it returns all 30 unique SerialNumber & MAC Addresses for the product.

SELECT DISTINCT c.PartNumber, SP.SerialNumber, SP.MAC
    FROM Order C
    INNER Join SO_MAC SP
    ON C.SO = SP.SO
    Where c.SO='847403' AND c.LI='1'

That's great that the above works and functions for what I need - but why if there are more than 1 "LineItems" does the JOIN create the duplicate results - and how should I be doing this query the right way so it doesn't change the results based on the number of "LineItems" on an "Order".
ProdigyOne2kAsked:
Who is Participating?

Improve company productivity with a Business Account.Sign Up

x
 
Chris LuttrellConnect With a Mentor Senior Database ArchitectCommented:
From what you describe it appears you do not have only one row in your Order table per order but one row per line item/PartNumber.  I thnik you are getting duplicates in your query because you are including the c.PartNumber which is probably different on each line.  Without seeing the data it is hard to know all the details and totally solve the problem.
Basically your Order table is not really normalized, i.e. distinct orders, but what most would consider the OrderDetail or OrderLineItems table.  Again, not seeing the whole picture I am having to make some assumptions here.
0
 
virtuadeptCommented:
Yes, if SO is not unique then the join will have duplicate rows.

If SO + LI = unique and are in both tables you could do this:

SELECT DISTINCT c.PartNumber, SP.SerialNumber, SP.MAC
    FROM Order C
    INNER Join SO_MAC SP
    ON C.SO = SP.SO
    AND C.LI = SP.LI
    Where c.SO='847403'
0
 
ProdigyOne2kAuthor Commented:
The only thing "SP" and "C" tables have in common is the "SO"
0
 
virtuadeptCommented:
The DISTINCT should be making the rows unique.  Can you post some example output?
0
 
ProdigyOne2kAuthor Commented:
This is the problem - I have normalized tables mixed with unnormalized tables causing the duplicates - no way to fix this the "right way" without doing some restructuring of the data
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.