SQL- calculating daily stock levels for month as aggregate of availability - sql

Question

I have a table containing following records of stocks from different depots in region. this contains:
itemName
startDate
endDate
quantity
The fields are
key(pk)
itemName- numeric code
startDate- date
endDate- date
amt- number
Sample data with 3 item types
1 101 Jan 1, 2013 Jan 14, 2013 15
2 101 Jan 12, 2013 Jan 15, 2013 3
3 102 Jan 4, 2013 Jan 26, 2013 7
4 102 Jan 6, 2013 Jan 12, 2013 19
5 103 Jan 15, 2013 Jan 16, 2013 3
6 103 Jan 12, 2013 Jan 21, 2013 19
How do I write a query that will get the number of items of each time every day in this period? Essentially I need to have a query that will add up applicable items between startDate and endDate. Thanks
I would want a final query result to look like that would add overlaps for each item
Jan 1 101 15
Jan 1 102 0
Jan 12 101 18
Jan 15 101 3
Jan 16 101 3
while I know i can do for a given date
SELECT item, sum(amt)
FROM [table]
WHERE (date>=startdate) AND (date<=enddate)
GROUP BY item
How do I enable it iterate for the whole month(Jan 1st to 31st) to produce such a report?

Answer 1

Here's what you need to do:
Create a table named [DayNumbers] and fill it with the numbers from 1 through 31:
DayNumber
---------
1
2
3
...
30
31
Now create a saved query in Access named [MonthDates] to create a row for each day in a specified month:
PARAMETERS SelectedYear Long, SelectedMonth Long;
SELECT DateSerial([SelectedYear], [SelectedMonth], DayNumber) AS StatusDate
FROM DayNumbers
WHERE Month(DateSerial([SelectedYear], [SelectedMonth], DayNumber)) = [SelectedMonth];
Note that the WHERE clause restricts the number of days to the actual number of days in the month (e.g., 30 for April).
Create another saved query in Access named [StockStatusRows] to create a row for each day and each item
SELECT StatusDate, itemName
FROM
MonthDates,
(
SELECT DISTINCT itemName FROM StockData
) AS Items;
For test data in [StockStatus] that looks like
key itemName startDate endDate amt
--- -------- ---------- ---------- ---
1 101 2013-01-01 2013-01-14 15
2 101 2013-01-12 2013-01-15 3
3 102 2013-01-04 2013-01-26 7
4 102 2013-01-06 2013-01-12 19
5 103 2013-01-15 2013-01-16 3
6 103 2013-01-12 2013-01-21 19
7 101 2013-01-30 2013-02-03 6
8 102 2013-02-05 2013-02-23 9
9 103 2013-02-07 2013-03-02 11
the [StockStatusRows] query will return
StatusDate itemName
---------- --------
2013-01-01 101
2013-01-02 101
2013-01-03 101
..
2013-01-30 101
2013-01-31 101
2013-01-01 102
2013-01-02 102
2013-01-03 102
...
2013-01-30 102
2013-01-31 102
2013-01-01 103
2013-01-02 103
2013-01-03 103
...
2013-01-30 103
2013-01-31 103
Now we can pull together the actual stock values like so:
SELECT ssr.StatusDate, ssr.itemName, Nz(sums.total, 0) AS TotalOnHand
FROM
StockStatusRows AS ssr
LEFT JOIN
(
SELECT StatusDate, itemName, Sum(amt) AS total
FROM
(
SELECT md.StatusDate, sd.itemName, sd.amt
FROM
StockData sd
INNER JOIN
MonthDates md
ON md.StatusDate>=sd.startDate
And md.StatusDate<=sd.endDate
)
GROUP BY StatusDate, itemName
) AS sums
ON (sums.itemName=ssr.itemName)
AND (sums.StatusDate=ssr.StatusDate)
ORDER BY ssr.StatusDate, ssr.itemName;
returning
StatusDate itemName TotalOnHand
---------- -------- -----------
2013-01-01 101 15
2013-01-01 102 0
2013-01-01 103 0
2013-01-02 101 15
2013-01-02 102 0
2013-01-02 103 0
2013-01-03 101 15
2013-01-03 102 0
2013-01-03 103 0
2013-01-04 101 15
2013-01-04 102 7
2013-01-04 103 0
2013-01-05 101 15
2013-01-05 102 7
2013-01-05 103 0
2013-01-06 101 15
2013-01-06 102 26
2013-01-06 103 0
...
2013-01-12 101 18
2013-01-12 102 26
2013-01-12 103 19
2013-01-13 101 18
2013-01-13 102 7
2013-01-13 103 19
2013-01-14 101 18
2013-01-14 102 7
2013-01-14 103 19
2013-01-15 101 3
2013-01-15 102 7
2013-01-15 103 22
2013-01-16 101 0
2013-01-16 102 7
2013-01-16 103 22
2013-01-17 101 0
2013-01-17 102 7
2013-01-17 103 19
...
2013-01-22 101 0
2013-01-22 102 7
2013-01-22 103 0
...
2013-01-31 101 6
2013-01-31 102 0
2013-01-31 103 0

Answer 2

select itemName from <Table-Name> where startDate>=(start-date) startDate<=(end-date) and endDate>=(start-date) and endDate<=(end-date) group by itemName.
This would calculate the sum of quantities of each product between (start-date) and (end-date).
If you want just total of all items irrespective of their type,
select sum(quantity) from <Table-Name> where startDate>=(start-date) startDate<=(end-date) and endDate>=(start-date) and endDate<=(end-date)
Hope this helps