Can't get missing days to show zero - tsql

Question

Here is what I've written - I'm trying to get the dates without transactions to just show zero for the field. I've gone to google and talked to everyone I know, this should work - but isn't :?
IF OBJECT_ID('tempdb..#D') IS NOT NULL
DROP TABLE #D;
CREATE TABLE #D
(
[Date] [DATE] NOT NULL,
PRIMARY KEY CLUSTERED ([Date] ASC)
);
DECLARE #CurrentDate DATE = GETDATE() - 95;
DECLARE #EndDate DATE = GETDATE();
WHILE #CurrentDate < #EndDate
BEGIN
INSERT INTO #D
(
[Date]
)
SELECT DATE = #CurrentDate;
SET #CurrentDate = DATEADD(DD, 1, #CurrentDate);
END;
--SELECT * FROM #D ORDER BY Date DESC
SELECT ITEM2_NUM AS 'Part Number',
COALESCE(SUM(TRANS_QTY), 0) 'Daily Usage',
D.Date AS 'Usage Date'
FROM #D AS D
LEFT OUTER JOIN dbo.W_INVENTORY_TRANS_F IT
ON IT.GL_DT = D.Date
LEFT JOIN dbo.W_BU_ITEM_D BI
ON BI.BUSINESS_UNIT_WID = IT.BUSINESS_UNIT_WID
AND BI.ITEM_WID = IT.ITEM_WID
WHERE DOCUMENT_TYPE_WID = 22
AND D.Date >= DATEADD(yy, -1, GETDATE())
AND IT.BUSINESS_UNIT_WID = '837'
AND IT.ITEM2_NUM = '10111'
AND BI.STOCKING_TYPE = 'P'
GROUP BY ITEM2_NUM,
D.Date
ORDER BY D.Date DESC;
Below is the results of what I get:
Part Number Daily Usage Usage Date
10111 -331.0000 2019-08-19
10111 -2617.0000 2019-08-16
10111 -418.0000 2019-08-15
10111 -471.0000 2019-08-14
10111 -1158.0000 2019-08-13
10111 -766.0000 2019-08-12
10111 -1385.0000 2019-08-09
This is what I want:
Part Number Daily Usage Usage Date
10111 -331 8/19/2019
10111 0 8/18/2019
10111 0 8/17/2019
10111 -2617 8/16/2019
10111 -418 8/15/2019
10111 -471 8/14/2019
10111 -1158 8/13/2019
10111 -766 8/12/2019
10111 0 8/11/2019
10111 0 8/10/2019
10111 -1385 8/9/2019

Answer 1

Your where clause is effectively changing your left join to an inner join.
That is because a left join returns nulls for rows that can't be found on the right table, and null compared to anything will always return unknown which is interpreted by the SQL Server as false.
What you need to do is move all the conditions that's referencing the right side tables into the on clause.
Also, you are grouping by ITEM2_NUM which doesn't make sense because it's already filtered out in the where clause.
Here's what should be a working version of your code (except the DOCUMENT_TYPE_WID column which I don't know what table it belongs to):
SELECT '10111' AS 'Part Number',
COALESCE(SUM(TRANS_QTY), 0) 'Daily Usage',
D.Date AS 'Usage Date'
FROM #D AS D
LEFT OUTER JOIN dbo.W_INVENTORY_TRANS_F IT
ON IT.GL_DT = D.Date
AND IT.BUSINESS_UNIT_WID = '837'
AND IT.ITEM2_NUM = '10111'
-- I had to guess where this column belongs, it might be on the BI table
AND IT.DOCUMENT_TYPE_WID = 22
LEFT JOIN dbo.W_BU_ITEM_D BI
ON BI.BUSINESS_UNIT_WID = IT.BUSINESS_UNIT_WID
AND BI.ITEM_WID = IT.ITEM_WID
AND BI.STOCKING_TYPE = 'P'
WHERE D.Date >= DATEADD(yy, -1, GETDATE())
GROUP BY D.Date
ORDER BY D.Date DESC;

Answer 2

Zohar was 100% correct - for those that end up here at some point below if the final code I ended up using.
IF OBJECT_ID('tempdb..#D') IS NOT NULL
DROP TABLE #D;
CREATE TABLE #D
(
[Date] [DATE] NOT NULL,
PRIMARY KEY CLUSTERED ([Date] ASC)
);
DECLARE #CurrentDate DATE = GETDATE() - 95;
DECLARE #EndDate DATE = GETDATE();
WHILE #CurrentDate < #EndDate
BEGIN
INSERT INTO #D
(
[Date]
)
SELECT DATE = #CurrentDate;
SET #CurrentDate = DATEADD(DD, 1, #CurrentDate);
END;
IF OBJECT_ID('tempdb..#DailyUsage') IS NOT NULL
DROP TABLE #DailyUsage;
CREATE TABLE #DailyUsage
(
BU_ITEM_WID INT,
TRANS_QTY DECIMAL(15, 4),
GL_DT DATETIME
);
INSERT INTO #DailyUsage
(
BU_ITEM_WID,
TRANS_QTY,
GL_DT
)
SELECT BU_ITEM_WID,
TRANS_QTY AS 'Daily Usage',
GL_DT
FROM dbo.W_INVENTORY_TRANS_F
WHERE 1 = 1
AND DOCUMENT_TYPE_WID = 22
AND GL_DT >= GETDATE() - 95;
CREATE NONCLUSTERED INDEX [IX_DailyUsage]
ON #DailyUsage (BU_ITEM_WID)
INCLUDE
(
TRANS_QTY,
GL_DT
);
WITH cte_ItemNums
AS (SELECT DISTINCT
IT.ITEM2_NUM,
IT.BU_ITEM_WID
FROM W_INVENTORY_TRANS_F IT
LEFT JOIN dbo.W_BU_ITEM_D BI
ON BI.BUSINESS_UNIT_WID = IT.BUSINESS_UNIT_WID
AND BI.ITEM_WID = IT.ITEM_WID
AND BI.STOCKING_TYPE = 'P'
WHERE 1 = 1
AND IT.DOCUMENT_TYPE_WID = 22
AND IT.BUSINESS_UNIT_WID = '837'
)
SELECT IT1.ITEM2_NUM,
COALESCE(SUM(IT2.TRANS_QTY), 0) AS 'Daily Usage',
D.Date AS 'Usage Date'
FROM #D AS D
LEFT OUTER JOIN cte_ItemNums IT1
ON 1 = 1
LEFT OUTER JOIN #DailyUsage IT2
ON IT2.GL_DT = D.Date
AND IT1.BU_ITEM_WID = IT2.BU_ITEM_WID
GROUP BY IT1.ITEM2_NUM,
D.Date;