Replace no result - sql

Question

I have a query like this:
SELECT TV.Descrizione as TipoVers,
sum(ImportoVersamento) as ImpTot,
count(*) as N,
month(DataAllibramento) as Mese
FROM PROC_Versamento V
left outer join dbo.PROC_TipoVersamento TV
on V.IDTipoVersamento = TV.IDTipoVersamento
inner join dbo.PROC_PraticaRiscossione PR
on V.IDPraticaRiscossioneAssociata = PR.IDPratica
inner join dbo.DA_Avviso A
on PR.IDDatiAvviso = A.IDAvviso
where DataAllibramento between '2012-09-08' and '2012-09-17' and A.IDFornitura = 4
group by V.IDTipoVersamento,month(DataAllibramento),TV.Descrizione
order by V.IDTipoVersamento,month(DataAllibramento)
This query must always return something. If no result is produced a
0 0 0 0
row must be returned. How can I do this. Use a isnull for every selected field isn't usefull.

Answer 1

Use a derived table with one row and do a outer apply to your other table / query.
Here is a sample with a table variable #T in place of your real table.
declare #T table
(
ID int,
Grp int
)
select isnull(Q.MaxID, 0) as MaxID,
isnull(Q.C, 0) as C
from (select 1) as T(X)
outer apply (
-- Your query goes here
select max(ID) as MaxID,
count(*) as C
from #T
group by Grp
) as Q
order by Q.C -- order by goes to the outer query
That will make sure you have always at least one row in the output.
Something like this using your query.
select isnull(Q.TipoVers, '0') as TipoVers,
isnull(Q.ImpTot, 0) as ImpTot,
isnull(Q.N, 0) as N,
isnull(Q.Mese, 0) as Mese
from (select 1) as T(X)
outer apply (
SELECT TV.Descrizione as TipoVers,
sum(ImportoVersamento) as ImpTot,
count(*) as N,
month(DataAllibramento) as Mese,
V.IDTipoVersamento
FROM PROC_Versamento V
left outer join dbo.PROC_TipoVersamento TV
on V.IDTipoVersamento = TV.IDTipoVersamento
inner join dbo.PROC_PraticaRiscossione PR
on V.IDPraticaRiscossioneAssociata = PR.IDPratica
inner join dbo.DA_Avviso A
on PR.IDDatiAvviso = A.IDAvviso
where DataAllibramento between '2012-09-08' and '2012-09-17' and A.IDFornitura = 4
group by V.IDTipoVersamento,month(DataAllibramento),TV.Descrizione
) as Q
order by Q.IDTipoVersamento, Q.Mese

Answer 2

Use COALESCE. It returns the first non-null value. E.g.
SELECT COALESCE(TV.Desc, 0)...
Will return 0 if TV.DESC is NULL.

Answer 3

You can try:
with dat as (select TV.[Desc] as TipyDesc, sum(Import) as ToImp, count(*) as N, month(Date) as Mounth
from /*DATA SOURCE HERE*/ as TV
group by [Desc], month(Date))
select [TipyDesc], ToImp, N, Mounth from dat
union all
select '0', 0, 0, 0 where (select count (*) from dat)=0
That should do what you want...

Answer 4

If it's ok to include the "0 0 0 0" row in a result set that has data, you can use a union:
SELECT TV.Desc as TipyDesc,
sum(Import) as TotImp,
count(*) as N,
month(Date) as Mounth
...
UNION
SELECT
0,0,0,0
Depending on the database, you may need a FROM for the second SELECT. In Oracle, this would be "FROM DUAL". For MySQL, no FROM is necessary