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;