What will be the output of

declare @t table(names varchar(MAX))
insert into @t
select 'Ram' union all
select 'Shyam' union all
select 'Jadhu' union all
select 'Madhu'


DECLARE @NamesList VARCHAR(8000);
SELECT @NamesList =
COALESCE(@NamesList + ', ', '') + CAST(names AS varchar(20))
FROM @t
SELECT IIF(CONCAT(@NamesList,NULL) IS NULL , @NamesList + NULL ,CONCAT(@NamesList,NULL))