mysql left join with 9 tables - php

Question

So the situation is I have a query that involves 9 tables and I need to write it so it returns all records even when the impactid in the workorderstates table is NULL.
Previous to the below query I noticed I wasn't getting all results that were "open" because initially I just had where workorderstates.impactid = impactdefiniton.impactid and in the situations where impactid is NULL in the workorderstates table this condition would not be true, thus eliminating records that should be returned because they are in fact "open".
So I devised this query below but every time I run it it will not work. It will will return not unique table alias workorder. If I use aliases for tables it just moves on the right tables in the join as not being unique. Can anyone offer me any help on restructuring the query so it will work? I've tried a lot of variations and interestingly enough the second query ALMOST works but it returns duplicate records (in this case four of the same record)
select workorder.workorderid, workorder.siteid,
FROM_UNIXTIME(workorder.CREATEDTIME/1000, '%m-%d-%Y %H:%i:%s') as createdate,
categoryname, IFNULL(workorderstates.impactid, "No Set") as impactid,
IFNULL(impactdefinition.name, "Not Set") as impactname, first_name,
sdorganization.name, statusname, title
from workorder, statusdefinition, sitedefinition, sdorganization,
prioritydefinition, categorydefinition, sduser, aaauser, workorderstates
left Join impactdefinition on workorderstates.impactid = impactdefinition.impactid
left join workorder on workorder.workorderid = workorderstates.workorderid
left join workorderstates on workorderstates.statusid = statusdefinition.statusid
left join workorder on workorder.siteid = sitedefinition.siteid
left join sitedefinition on sitedefinition.siteid = sdorganization.org_id
left join workorderstates on workorderstates.categoryid = categorydefinition.categoryid
left join workorder on workorder.requesterid = sduser.userid
left join sduser on sduser.userid = aaauser.user_id
where statusname='Open' and workorder.createdtime >= '1352678400000'
and sdorganization.name='MAPL'
order by workorder.workorderid
Query that almost works but is ugly (returns duplicated records):
select workorder.workorderid, workorder.siteid,
FROM_UNIXTIME(workorder.CREATEDTIME/1000, '%m-%d-%Y %H:%i:%s') as createdate,
categoryname, IFNULL(workorderstates.impactid, "No Set") as impactid,
IFNULL(impactdefinition.name, "Not Set") as impactname, first_name,
sdorganization.name, statusname, title
from workorder, statusdefinition, sitedefinition, sdorganization,
prioritydefinition, categorydefinition, sduser, aaauser, workorderstates
left Join impactdefinition on workorderstates.impactid = impactdefinition.impactid
where workorder.workorderid = workorderstates.workorderid
and workorderstates.statusid = statusdefinition.statusid
and workorder.siteid = sitedefinition.siteid
and sitedefinition.siteid = sdorganization.org_id
and workorderstates.categoryid = categorydefinition.categoryid
and workorder.requesterid = sduser.userid and sduser.userid = aaauser.user_id
and statusname='Open' and workorder.createdtime >= '1352678400000'
and sdorganization.name='MAPL'
order by workorder.workorderid
Any ideas of how to get this query working??? Thanks guys!

Answer 1

I took a look at your query and I think you have some basic misunderstandings about JOINs and how to write them. It's like you're just guessing at syntax at random, and that's not the way to write code.
I examined your query and converted it into SQL-92 syntax. I had to make some inferences about join conditions, so I can't guarantee it's correct for your application, but it's a lot closer to a legal query.
Only I couldn't find any condition in your example for the join to your prioritydefinition table. That's likely to be the cause of your duplicate rows. You're generating what's called a Cartesian product.
select workorder.workorderid, workorder.siteid,
FROM_UNIXTIME(workorder.CREATEDTIME/1000, '%m-%d-%Y %H:%i:%s') as createdate,
categoryname, IFNULL(workorderstates.impactid, "No Set") as impactid,
IFNULL(impactdefinition.name, "Not Set") as impactname, first_name,
sdorganization.name, statusname, title
from workorder
inner join statusdefinition on workorderstates.statusid = statusdefinition.statusid
inner join sitedefinition on workorder.siteid = sitedefinition.siteid
inner join sdorganization on sitedefinition.siteid = sdorganization.org_id
inner join prioritydefinition ...NO JOIN CONDITION FOUND...
inner join categorydefinition on workorderstates.categoryid = categorydefinition.categoryid
inner join sduser on workorder.requesterid = sduser.userid
inner join aaauser on sduser.userid = aaauser.user_id
inner join workorderstates on workorder.workorderid = workorderstates.workorderid
left Join impactdefinition on workorderstates.impactid = impactdefinition.impactid
where statusname='Open'
and workorder.createdtime >= '1352678400000'
and sdorganization.name='MAPL'
order by workorder.workorderid
You really need to get someone who knows your application and also knows how to write SQL to tutor you before you write any more SQL joins.

Answer 2

I too reformatted your query but have it more visually hierarchical to show relations from the first (left-side) table to what it is getting its details from (right-side) table. As Bill mentioned, you had an extra table that was not doing anything and thus your Cartesian product.
Now, if you ARE stuck and have no one else to really help, here is a basic of LEFT-JOIN vs INNER-JOIN. Left-join basically says I want every record from the table on the left (as I have listed first) REGARDLESS of there being a record found on the right side. If there IS a match, great, no problem... but if no match, your query will still run.
So, I've set to all LEFT-JOINs. You can change as needed for those you know MUST always exist... such as a work order is entered by a "user". So that you could change. Hopefully this helps you out. Also look at how I've nested from work order to work order states and from work order states to get the corresponding status definition and other things associated with the work order states table. Others were directly related with the work order, so those are at THAT hierarchical level.
One last note... not all your fields were table.field reference (which I changed to aliases to help readability). QUALIFY ALL your fields so you and others trying to help, or read your code in the future know the origin of the field, not just guessing (its in one of the tables)
select
WO.workorderid,
WO.siteid,
FROM_UNIXTIME(WO.CREATEDTIME/1000, '%m-%d-%Y %H:%i:%s') as createdate,
categoryname,
IFNULL(WOS.impactid, "No Set") as impactid,
IFNULL(ImpD.name, "Not Set") as impactname, first_name,
SDO.name,
statusname,
title
from
workorder WO
LEFT JOIN workorderstates WOS
ON WO.workorderid = WOS.workorderid
LEFT JOIN statusdefinition StatD
ON WOS.statusid = StatD.statusid
LEFT JOIN categorydefinition CatD
ON WOS.categoryid = CatD.categoryid
LEFT JOIN impactdefinition ImpD
ON WOS.impactid = ImpD.impactid
LEFT JOIN sitedefinition SiteD
ON WO.siteid = SiteD.siteid
LEFT JOIN sdorganization SDO
ON SiteD.siteid = SDO.org_id
and SDO.name = 'MAPL'
LEFT JOIN sduser U
ON WO.requesterid = U.userid
LEFT JOIN aaauser AU
ON U.userid = AU.user_id
where
statusname = 'Open'
and WO.createdtime >= '1352678400000'
order by
WO.workorderid