Creating Daily In-Use table w/ Zeros When NULL - sql

Question

Hello Stack Community,
I am not sure if I titled this accurately, but I am attempting to create a table that tracks the daily in-use quantity by product code. Currently my code drops dates where a product isn't in-use whereas I need that to show as a 0.
My thoughts where that by using the date from the date table that my LEFT OUTER JOIN with the ISNULL on the field would produce a 0, but nay.
Here is my code, with a screenshot of what it outputs with the red square highlighting where it's missing date records that I need to show as 0 :
SELECT
DD.DATE,
DE.PRODUCT_CODE,
--OOC = OUT OF CONTEXT, EITHER ISN'T CHARGEABLE OR ISN'T CURRENTLY ACTIVE
ISNULL(SUM(LIDV.QTY - LIDV.QTYSUB),0),
OD.LOCATION,
OD.SOURCE
FROM Dim_Date AS DD
LEFT OUTER JOIN ORDERv_DatesDays AS OD ON DD.DATE BETWEEN OD.SHIP_DATE AND OD.adjRETURN_DATE
LEFT OUTER JOIN FACT_Orders_LIDs AS LIDV ON LIDV.SORDERID_DAX = OD.SORDERID_DAX
LEFT OUTER JOIN DIM_ECODES AS DE ON DE.PRODUCT_CODE = LIDV.eCODE
WHERE
--DD.DATE = '3/1/2017' AND
DD.DATE BETWEEN '1/1/2017' AND EOMONTH( DATEADD( MONTH , -1, CURRENT_TIMESTAMP ) ) AND
DE.PRODUCT_CODE = '07316-' AND
YEAR(DD.DATE) = 2017
GROUP BY
DD.DATE,
DE.PRODUCT_CODE,
OD.LOCATION,
OD.SOURCE
ORDER BY
DD.DATE
I also thought, since I'm no SQL expert, that perhaps I need to just create a table with each product code and date for a specified date range but I got tripped up trying to create that as well.
Thank you for any assistance, if I need to add more info just let me know what I'm missing.

Answer 1

This WHERE predicate is killing your left join:
DE.PRODUCT_CODE = '07316-' AND
If product_code 07316 was not "out on loan" (or whatever) between Feb 24 and April 6 then all those rows would have looked like:
DATE PRODUCT_CODE INUSE LOCATION
2017-02-25 NULL NULL NULL
2017-02-26 NULL NULL NULL
2017-02-27 NULL NULL NULL
2017-02-28 NULL NULL NULL
...
2017-04-05 NULL NULL NULL
But, that NULL in product_code means that when the where clause asks "is NULL equal to 07316- ?" the answer is false, so the row diasppears from the resultset
Consider
LEFT OUTER JOIN DIM_ECODES AS DE
ON
DE.PRODUCT_CODE = LIDV.eCODE AND
DE.PRODUCT_CODE = '07316-'
You might also want to make some changes in the SELECT block too:
'07316-' as PRODUCT_CODE,
COALESCE(INUSE,0) AS INUSE
It might make more sense to you to write it like this:
FROM
Dim_Date AS DD
LEFT OUTER JOIN
(
SELECT
OD.SHIP_DATE,
OD.adjRETURN_DATE,
LIDV.QTY,
LIDV.QTYSUB,
OD.LOCATION,
OD.SOURCE
FROM
ORDERv_DatesDays AS OD
INNER JOIN FACT_Orders_LIDs AS LIDV ON LIDV.SORDERID_DAX = OD.SORDERID_DAX
INNER JOIN DIM_ECODES AS DE ON DE.PRODUCT_CODE = LIDV.eCODE
WHERE
DE.PRODUCT_CODE = '07316-'
) x
ON DD.DATE BETWEEN x.SHIP_DATE AND x.adjRETURN_DATE
WHERE
This is "list of dates on the left" and "any relevant data, already joined together and where'd on the right"
It should also be noted that if you're doing this for multiple product codes, to prevent just a single date row if both product 07316 and 07317 are in use on the 28th Feb you'd need to:
FROM
(
SELECT DISTINCT DD.DATE, DE.PRODUCT_CODE
FROM Dim_Date AS DD CROSS JOIN DIM_ECODES DE
WHERE ..date range clause..
)
This takes your list of dates, and crosses it with your list of prod codes, so you can be certain there are at least these two rows:
2017-02-28 07316-
2017-02-28 07317-
Then when you left join the products on date and product code, both those rows' data survive the left join, and become associated with nulls:
2017-02-28 07316- NULL NULL
2017-02-28 07317- NULL NULL
Without doing that CROSS, you'd have just one row (null in product code)