Prova detta:
declare @s1 varchar(3000) ;
declare @xml xml,@str varchar(100),@delimiter varchar(10), @out varchar(max);;
select @delimiter =' '
select @s1 = 'This is a string';
select @s1 = 'This is a string ';
select @s1 = 'This is a string ';
select @s1 = 'This is a string';
select @xml = cast(('<X>'+replace(@s1,@delimiter ,'</X><X>')+'</X>') as xml)
select top 3 @out =
COALESCE(@out + ' ', '') + C.value('.', 'varchar(100)')
from @xml.nodes('X') as X(C)
where LEN(C.value('.', 'varchar(10)')) > 0
select @out