T-SQL NULL-Friendly Query - sql

Question

I have a table "tblSalesOrder" in Microsoft T-SQL with some sample records:
SalesOrderID OrderDate ItemID Quantity PromotionCode
====================================================================
1 2014-09-01 100 5 NULL
2 2014-09-01 120 10 ABC
3 2014-09-05 150 7 NULL
4 2014-09-08 200 15 NULL
I need to return NULL-friendly resultset for records which do not exist.
As an example, I want a monthly query for September 2014:
SELECT SalesOrderID, OrderDate, ItemID, Quantity, PromotionCode
FROM tblSalesOrder
WHERE OrderDate = BETWEEN '2014-09-01' AND '2014-09-30'
I need it to return at least 1 row for each day (i.e. 0 valued row, if the entry for that day is not available)
SalesOrderID OrderDate ItemID Quantity PromotionCode
====================================================================
1 2014-09-01 100 5 NULL
2 2014-09-01 120 10 ABC
0 2014-09-02 0 0 0
0 2014-09-03 0 0 0
0 2014-09-04 0 0 0
3 2014-09-05 150 7 NULL
0 2014-09-06 0 0 0
0 2014-09-07 0 0 0
4 2014-09-08 200 15 NULL
0 2014-09-09 0 0 0
...
...
...
0 2014-09-30 0 0 0

Answer 1

master..spt_values is a table in all microsoft sql databases containing 2506 rows, by cross joining, it will have 2506*2506 rows to calculate dates between from and to. Other tables can be used as well, this is just a table used to create the dates. A calendar table would be even easier to use.
The EXCEPT will remove all dates already in use. Then by combining the rows from tblSalesOrder and CTE with union all, empty days will be filled with the required hardcoded values:
DECLARE #from date = '2014-09-01'
DECLARE #to date = '2014-09-30'
;WITH CTE as
(
SELECT top (case when #to < #from then 0 else datediff(day, #from, #to) + 1 end)
dateadd(day, row_number() over (order by (select 1)) - 1, #from) OrderDate
FROM
master..spt_values t1
CROSS JOIN
master..spt_values t2
EXCEPT
SELECT
OrderDate
FROM
tblSalesOrder
)
SELECT
0 SalesOrderID, OrderDate, 0 ItemID, 0 Quantity, '0' PromotionCode
FROM
CTE
UNION ALL
SELECT
SalesOrderID, OrderDate, ItemID, Quantity, PromotionCode
FROM
tblSalesOrder
ORDER BY
OrderDate, SalesOrderId

Answer 2

You can join the a date parameter in an empty select and coalesce the values:
select coalesce(t.SalesOrderID, 0) SalesOrderID
, coalesce(t.OrderDate, d.OrderDate) OrderDate
, coalesce(t.ItemID, 0) ItemID
, coalesce(t.Quantity, 0) Quantity
, coalesce(t.PromotionCode, 0) PromotionCode
from (select #dateParameter OrderDate) d
left
outer
join ( SELECT SalesOrderID, OrderDate, ItemID, Quantity, PromotionCode
FROM tblSalesOrder
) t
on t.OrderDate = d.OrderDate

Answer 3

DECLARE #startDate date= '20140901'
,#endDate date = '20140930';
WITH Calendar as (
SELECT #startDate as OrderDate
UNION ALL
SELECT DATEADD(DAY, 1, OrderDate) as OrderDate
FROM Calendar
WHERE OrderDate < #endDate
)
SELECT coalesce(t.SalesOrderID, 0) SalesOrderID
, coalesce(t.OrderDate, Calendar.OrderDate) OrderDate
, coalesce(t.ItemID, 0) ItemID
, coalesce(t.Quantity, 0) Quantity
, CASE WHEN t.OrderDate IS NULL THEN '0' ELSE t.PromotionCode END as PromotionCode FROM Calendar
LEFT JOIN tblSalesOrder t ON Calendar.OrderDate = t.OrderDate
ORDER BY Calendar.OrderDate, t.SalesOrderID
OPTION (MAXRECURSION 0);