Select Statement Return 0 if Null - sql

Question

I have the following query
SELECT ProgramDate, [CountVal]= COUNT(ProgramDate)
FROM ProgramsTbl
WHERE (Type = 'Type1' AND ProgramDate = '10/18/11' )
GROUP BY ProgramDate
What happens is that if there is no record that matches the Type and ProgramDate, I do not get any records returned.
What I like to have outputted in the above is something like the following if there is no values returned. Notice how for the CountVal we have 0 even if there are no records returned that fit the match condition:
ProgramDate CountVal
10/18/11 0

Answer 1

This is a little more complicated than you would like however, it is very possible. You will first have to create a temporary table of dates. For example, the query below creates a range of dates from 2011-10-11 to 2011-10-20
CREATE TEMPORARY TABLE date_stamps AS
SELECT (date '2011-10-10' + new_number) AS date_stamp
FROM generate_series(1, 10) AS new_number;
Using this temporary table, you can select from it and left join your table ProgramsTbl. For example
SELECT date_stamp,COUNT(ProgramDate)
FROM date_stamps
LEFT JOIN ProgramsTbl ON ProgramsTbl.ProgramDate = date_stamps.date_stamp
WHERE Type = 'Type1'
GROUP BY ProgramDate;

Answer 2

Select ProgramDate, [CountVal]= SUM(occur)
from
(
SELECT ProgramDate, 1 occur
FROM ProgramsTbl
WHERE (Type = 'Type1' AND ProgramDate = '10/18/11' )
UNION
SELECT '10/18/11', 0
)
GROUP BY ProgramDate

Answer 3

Because each SELECT statement is really building a table of records you can use a SELECT query to build a table with both the program count and a default count of zero. This would require two SELECT queries (one to get the actual count, one to get the default count) and using a UNION to combine the two SELECT results into a single table.
From there you can SELECT from the UNIONed table to sum the CountVals (if the programDate occurs in the ProgramTable the CountVal will be
CountVal of the first query if it exists(>0) + CountVal of the second query (=0)).
This way even if there are no records for the desired programDate in ProgramTable you will get a record back indicating a count of 0.
This would look like:
SELECT ProgramDate, SUM(CountVal)
FROM
(SELECT ProgramDate, COUNT(*) AS CountVal
FROM ProgramsTbl
WHERE (Type = 'Type1' AND ProgramDate = '10/18/11' )
UNION
SELECT '10/18/11' AS ProgramDate, 0 AS CountVal) T1

Answer 4

Here's a solution that works on SQL Server; not sure about other db platforms:
DECLARE #Type VARCHAR(5) = 'Type1'
, #ProgramDate DATE = '10/18/2011'
SELECT pt.ProgramDate
, COUNT(pt2.ProgramDate)
FROM ( SELECT #ProgramDate AS ProgramDate
, #Type AS Type
) pt
LEFT JOIN ProgramsTbl pt2 ON pt.Type = pt2.Type
AND pt.ProgramDate = pt2.ProgramDate
GROUP BY pt.ProgramDate

Answer 5

Grunge but simple and efficient
SELECT '10/18/11' as 'Program Date', count(*) as 'count'
FROM ProgramsTbl
WHERE Type = 'Type1' AND ProgramDate = '10/18/11'

Answer 6

Try something along these lines. This will establish a row with a date of 10/18/11 that will definitely return. Then you left join to your actual data to get your desired count (which can now return 0 if there are no corresponding rows).
To do this for more than 1 date, you'd want to build a Date table that holds a list of all dates you want to query (so substitute the "select '10/18/11'" with "select Date from DateTbl").
SELECT ProgDt.ProgDate, [CountVal]= COUNT(ProgramsTbl.ProgramDate)
FROM (SELECT '10/18/11' as 'ProgDate') ProgDt
LEFT JOIN ProgramsTbl
ON ProgDt.ProgDate = ProgramsTbl.ProgramDate
WHERE (Type = 'Type1')
GROUP BY ProgDt.ProgDate
To create a date table that you can use for querying, do this (assumes SQL Server 2005+):
create table Dates (MyDate datetime)
go
insert into Dates
select top 100000 row_number() over (order by s1.name)
from master..spt_values s1, master..spt_values s2
go