Trouble with pulling distinct data - sql

Question

Ok this is hard to explain partially because I'm bad at sql but this code isn't doing exactly what I want it to do. I'll try to explain what it is supposed to do as best I can and hopefully someone can spot a glaring mistake. I'm sorry about the long winded explanation but there is a lot going on here and I really could use the help.
The point of this script is to search for parts which need to be obsoleted. in other words they haven't been used in three years and are still active.
When we obsolete part, "part.status" is set to 'O'. It is normally null. Also, the word 'OBSOLETE' is usually written in to "part.description"
The "WORK_ORDER" contains every scheduled work order. These are defined by base,lot, and sub ID's. It also contains many dates such as the date when the work order was closed.
the "REQUIREMENT" table contains all the parts require for each job. many jobs may require multiple parts, some at different legs of the job. The way this is handled is that for a given "REQUIREMENT.WORKORDER_BASE_ID" and "REQUIREMENT.WORKORDER_LOT_ID", they may be listed on a dozen or so subsequent rows. Each line specifies a different "REQUIREMENT.PART_ID". The sub id separates what leg of the job that the part is needed. All of the parts I care about start with 'PCH'
When I run this code it returns 14 lines, I happen to know it should be returning about 39 right now. I believe the screwy part starts at line 17. I found that code on another form hoping that it would help solve the original problem. Without that code, I get like 27K lines because the DB is pulling every criteria matching requirement from every criteria matching work order. Many of these parts are used on multiple jobs. I've also tried using DISTINCT on REQUIREMENT.PART_ID which seems like it should solve the problem. Alas it doesn't.
So I know despite all the information I probably still didn't give nearly enough. Does anyone have any suggestions?
SELECT
PART.ID [Engr Master]
,PART.STATUS [Master Status]
,WO.CLOSE_DATE
,PT.ID [Die]
,PT.STATUS [Die Status]
FROM PART
CROSS APPLY(
SELECT
WORK_ORDER.BASE_ID
,WORK_ORDER.LOT_ID
,WORK_ORDER.SUB_ID
,WORK_ORDER.PART_ID
,WORK_ORDER.CLOSE_DATE
FROM WORK_ORDER
WHERE
GETDATE() - (360*3) > WORK_ORDER.CLOSE_DATE
AND PART.ID = WORK_ORDER.PART_ID
AND PART.STATUS ='O'
)WO
CROSS APPLY(
SELECT
REQUIREMENT.WORKORDER_BASE_ID
,REQUIREMENT.WORKORDER_LOT_ID
,REQUIREMENT.WORKORDER_SUB_ID
,REQUIREMENT.PART_ID
FROM REQUIREMENT
WHERE
WO.BASE_ID = REQUIREMENT.WORKORDER_BASE_ID
AND WO.LOT_ID = REQUIREMENT.WORKORDER_LOT_ID
AND WO.SUB_ID = REQUIREMENT.WORKORDER_SUB_ID
AND REQUIREMENT.PART_ID LIKE 'PCH%'
)REQ
CROSS APPLY(
SELECT
PART.ID
,PART.STATUS
FROM PART
WHERE
REQ.PART_ID = PART.ID
AND PART.STATUS IS NULL
)PT
ORDER BY PT.ID

Answer 1

This is difficult to understand without any sample data, but I took a stab at it anyway. I removed the second JOIN to PART (that had alias PART1) as it seemed unecessary. I also removed the subquery that was looking for parts HAVING COUNT(PART_ID) = 1
The first JOIN to PART should be done on REQUIREMENT.PART_ID = PART.PART_ID as the relationship as already been defined from WORK_ORDER to REQUIREMENT, hence you can JOIN PART directly to REQUIREMENT at this point.
EDIT 03/23/2015
If I understand this correctly, you just need a distinct list of PCH parts, and their respective last (read: MAX) CLOSE_DATE. If that is the case, here is what I propose.
I broke the query up into a couple of CTE's. The first CTE is simply going through the PART table and pulling out a DISTINCT list of PCH parts, grouping by PART_ID and DESCRIPTION.
The second CTE, is going through the REQUIREMENT table, joining to the WORK_ORDER table and, for each PART_ID (handled by the PARTITION) assigning the CLOSE_DATE a ROW_NUMBER in descending order. This will ensure that each ROW_NUMBER with a value of "1" will be the Max CLOSE_DATE for each PART_ID.
The final SELECT statement simply JOINS the two Cte's on PART_ID, filtering where LastCloseDate = 1 (the ROW_NUMBER assigned in the second CTE).
If I understand the requirements correctly, this should give you the desired results.
Additionally, I removed the filter WHERE PART.DESCRIPTION NOT LIKE 'OB%' because we're already filtering by PART.STATUS IS NULL and you stated above that an 'O' is placed in this field for Obsolete parts. Also, [DIE] and [ENGR MASTER] have the same value in the 27 rows being pulled before, so I just used the same field and labeled them differently.
; WITH Parts AS(
SELECT prt.PART_ID AS [ENGR MASTER]
, prt.DESCRIPTION
FROM PART prt
WHERE prt.STATUS IS NULL
AND prt.PART_ID LIKE 'PCH%'
GROUP BY prt.ID, prt.DESCRIPTION
)
, LastCloseDate AS(
SELECT req.PART_ID
, wrd.CLOSE_DATE
, ROW_NUMBER() OVER(PARTITION BY req.PART_ID ORDER BY wrd.CLOSE_DATE DESC) AS LastCloseDate
FROM REQUIREMENT req
INNER JOIN WORK_ORDER wrd
ON wrd.BASE_ID = req.WORKORDER_BASE_ID
AND wrd.LOT_ID = req.WORKORDER_LOT_ID
AND wrd.SUB_ID = req.WORKORDER_SUB_ID
WHERE wrd.CLOSE_DATE IS NOT NULL
AND GETDATE() - (365 * 3) > wrd.CLOSE_DATE
)
SELECT prt.PART_ID AS [DIE]
, prt.PART_ID AS [ENGR MASTER]
, prt.DESCRIPTION
, lst.CLOSE_DATE
FROM Parts prt
INNER JOIN LastCloseDate lst
ON prt.PART_ID = lst.PART_ID
WHERE LastCloseDate = 1