Join table with dates list - include reference on NULLs - sql

Question

More brain freeze moments from me. I'm sure this will be an easy one.
I have two tables. One is a list of part usage by week. This is called TransactionsPerWeek and looks like this:
ItemPK xWeek xYear TotalQty
1234 2 2019 65
1234 4 2019 15
1234 5 2019 50
I also have a DateList table that has week numbers and years in it
xWeek xYear
1 2019
2 2019
3 2019
etc.
When I right join the two together on week and year I get
ItemPK xWeek xYear TotalQty
NULL 1 2019 0
1234 2 2019 65
NULL 3 2019 0
1234 4 2019 15
1234 5 2019 50
What I need is to have the ItemPK on every line, even if the TotalQty is 0. So in effect, I need:
ItemPK xWeek xYear TotalQty
1234 1 2019 0
1234 2 2019 65
1234 3 2019 0
1234 4 2019 15
1234 5 2019 50
This is my code...
SELECT itemfk,
dates.year,
dates.week,
isnull(transactionsperweek.TotalQty,0) as TotalQty
from (
SELECT iit.ItemFK,
year(iit.transactiondate) xYear,
datepart(wk,iit.transactiondate) xWeek,
abs(sum(iit.quantity)) TotalQty
from iteminventorytransaction iit
INNER JOIN ItemInventoryTransactionType iitt on ItemInventoryTransactionTypePK = iit.ItemInventoryTransactionTypeFK
where iit.itemfk = 5311
and iit.ItemInventoryTransactionTypeFK in (10,8)
and iit.TransactionDate BETWEEN
-- 1 year up to the sunday of last week
DateAdd(wk,-51,DATEADD(day,-1 - (DATEPART(weekday, GETDATE()) + ##DATEFIRST - 2) % 7,GETDATE()))
AND DATEADD(day,-1 - (DATEPART(weekday, GETDATE()) + ##DATEFIRST - 2) % 7,GETDATE())
AND Quantity < 0
group by iit.itemfk,
year(iit.transactiondate),
datepart(wk,iit.transactiondate)
) transactionsPerWeek
RIGHT JOIN (
select year,
week
from DatesList
where date > DateAdd(wk,-51,DATEADD(day,-1 - (DATEPART(weekday, GETDATE()) + ##DATEFIRST - 2) % 7,GETDATE()))
AND date < DATEADD(day,-1 - (DATEPART(weekday, GETDATE()) + ##DATEFIRST - 2) % 7,GETDATE())
group by year,
week
) Dates ON dates.week = transactionsPerWeek.xWeek
AND dates.year = transactionsPerWeek.xYear
where week not in (52,53)
Hope this is clear enough. Thanks in advance.

Answer 1

You can use recursive cte :
with cte as (
select 1 as id, max(xWeek) as maxwk
from TransactionsPerWeek
union all
select id + 1, maxwk
from cte c
where c.id < maxwk
)
select coalesce(wk.ItemPK, wk1.ItemPK) as ItemPK, c.id as xWeek, wk.xYear, wk.TotalQty
from cte c left join
TransactionsPerWeek wk
on wk.xWeek = c.id outer apply
( select top (1) wk1.ItemPK
from TransactionsPerWeek wk1
where wk1.xWeek >= c.id and wk1.xWeek is not null
order by wk1.xWeek
) wk1;

Answer 2

Ok, so I did what #larnu suggested and cross joined the item with the dates, then left joined it to the transactionsperweek table and it worked. Thank you.
This is my code now;
SELECT itempk, week, year
, ISNULL(transactionsPerWeek.TotalQty,0) as TotalQty
from item
CROSS JOIN
(
select year, week from DatesList where date >
DateAdd(wk,-51,DATEADD(day,-1 - (DATEPART(weekday, GETDATE()) + ##DATEFIRST - 2) % 7,GETDATE()))
AND date <
DATEADD(day,-1 - (DATEPART(weekday, GETDATE()) + ##DATEFIRST - 2) % 7,GETDATE())
group by year, week
) dates
LEFT JOIN
(
SELECT iit.ItemFK, year(iit.transactiondate) xYear, datepart(wk,iit.transactiondate) xWeek, abs(sum(iit.quantity)) TotalQty from iteminventorytransaction iit
INNER JOIN ItemInventoryTransactionType iitt on ItemInventoryTransactionTypePK = iit.ItemInventoryTransactionTypeFK
where iit.itemfk = 5311 and iit.ItemInventoryTransactionTypeFK in (10,8)
and iit.TransactionDate BETWEEN
-- 1 year up to the sunday of last week
DateAdd(wk,-51,DATEADD(day,-1 - (DATEPART(weekday, GETDATE()) + ##DATEFIRST - 2) % 7,GETDATE()))
AND
DATEADD(day,-1 - (DATEPART(weekday, GETDATE()) + ##DATEFIRST - 2) % 7,GETDATE())
AND Quantity < 0
group by iit.itemfk, year(iit.transactiondate), datepart(wk,iit.transactiondate)
) transactionsPerWeek
ON itempk = transactionsperweek.ItemFK and transactionsPerWeek.xYear = dates.year and transactionsPerWeek.xWeek = dates.week
where itempk = 5311

Answer 3

Use a cross join to generate the rows and a left join to bring in the results you already have.
Your question explicitly states that you have two tables. Hence, I don't know what your SQL code is doing, because it is not referencing those tables. So, based on the description:
select i.ItemPK, d.xWeek, d.xYear,
coalesce(TotalQty, 0) as TotalQty
from (select distinct itemPK from TransactionsPerWeek
) i cross join
DateList d left join
TransactionsPerWeek t
on t.itemPK = i.itemPK and
t.xWeek = d.xWeek and
t.xYear = d.xYear;
Of course if the "tables" are really subqueries, then I would recommend using CTEs and still this basic query structure.