How to have a NULL instead of No Value from a query - sql

Question

I had a query like:
SELECT ISNULL(S.Name+'.'+T.Name,'Table Not Found')
FROM DataProfile.Tables T
INNER JOIN DataProfile.Schemas S ON T.schemaId=S.Id
WHERE S.Name+'.'+T.Name=#TableName
Then I tried
IIF(LEN(S.Name+'.'+T.Name)>0,S.Name+'.'+T.Name,NULL)
But when it doesn't find the named table returns not output, Value or Null value or anything I can work on.
This is going to be used as a crosscheck.
Does anybody have any idea?

Answer 1

Thanks for those who payed attention to what I exactly asked and for their responses.
Here the way I tried:
DECLARE #Check NVARCHAR(MAX) = 'TABLE DOES NOT FOUND'
SELECT #Check= S.Name + '.' + T.Name
FROM DataProfile.Tables T
INNER JOIN DataProfile.Schemas S ON T.schemaId=S.Id
WHERE S.Name+'.'+T.Name=#TableName
SELECT #CHECK
And That Worked for me

Answer 2

this will always return a row:
select v.TableName, ISNULL(found.result, 'not found') result
from (values(#TableName))v(TableName)
outer apply (
select CAST('found' as nvarchar(11)) result
from DataProfile.Tables T
join DataProfile.Schemas S ON T.schemaId=S.Id
where S.Name+'.'+T.Name=v.TableName
)found

Answer 3

you should try this
SELECT CASE WHEN (LEN(S.Name + '.' + T.Name))> 1 THEN S.Name + '.' + T.Name ELSE NULL END
So you qry will look like
SELECT CASE
WHEN (LEN(S.Name + '.' + T.Name))> 1 THEN
S.Name + '.' + T.Name
ELSE
NULL -- Here use any expresion which you want
END
FROM DataProfile.Tables T
INNER JOIN DataProfile.Schemas S ON T.schemaId=S.Id
WHERE S.Name+'.'+T.Name=#TableName
Here you are using ISNULL(S.Name+'.'+T.Name,'Table Not Found') which never return false part due to if S.Name and T.Name both are null then still that value will be '.'

Answer 4

Try doing it this way:
with table_qry as
(
select S.Name as SName, T.Name as TName
from DataProfile.Tables T
inner join DataProfile.Schemas S
on T.SchemaId = S.Id
where S.Name+'.'+T.Name = #TableName
)
select case when (select count(1) from table_qry) > 0 then
SName+'.'+TName else 'Table Not Found' end as TableName
from table_qry;
There are more elegant ways of doing it, but this should work just fine for you.