Icementhols Icementhols - 2 months ago 12
SQL Question

Changing a SUM returned NULL to zero

I have a Stored Procedure as follows:

CREATE PROC [dbo].[Incidents]
(@SiteName varchar(200))

AS

SELECT

(
SELECT SUM(i.Logged)
FROM tbl_Sites s
INNER JOIN tbl_Incidents i
ON s.Location = i.Location
WHERE s.Sites = @SiteName AND i.[month] = DATEADD(mm, DATEDIFF(mm, 0, GetDate()) -1,0)
GROUP BY s.Sites
) AS LoggedIncidents

'tbl_Sites contains a list of reported on sites.
'tbl_Incidents containts a generated list of total incidents by site/date (monthly)
'If a site doesnt have any incidents that month it wont be listed.


The problem I'm having is that a site doesnt have any Incidents this month and as such i get a NULL value returned for that site when i run this sproc, but i need to have a zero/0 returned to be used within a chart in SSRS.

I've tried the using coalesce and isnull to no avail.

SELECT COALESCE(SUM(c.Logged,0))
SELECT SUM(ISNULL(c.Logged,0))


Is there a way to get this formatted correctly?

Cheers,

Lee

Answer

Put it outside:

SELECT COALESCE(

(  
    SELECT SUM(i.Logged)  
    FROM tbl_Sites s  
    INNER JOIN tbl_Incidents i  
    ON s.Location = i.Location  
    WHERE s.Sites = @SiteName AND i.[month] = DATEADD(mm, DATEDIFF(mm, 0, GetDate()) -1,0)  
    GROUP BY s.Sites  
), 0)  AS LoggedIncidents

If you are returning multiple rows, change INNER JOIN to LEFT JOIN

SELECT COALESCE(SUM(i.Logged),0)
FROM tbl_Sites s  
LEFT JOIN tbl_Incidents i  
ON s.Location = i.Location  
WHERE s.Sites = @SiteName AND i.[month] = DATEADD(mm, DATEDIFF(mm, 0, GetDate()) -1,0)  
GROUP BY s.Sites  

By the way, don't put any function or expression inside aggregate functions if it's not warranted, e.g. don't put ISNULL, COALESCE inside of SUM, using function/expression inside aggregation cripples performance, the query will be executed with table scan