If you only want to return a few characters of your long string, you can use:
select
left(col, 15) + '...' col
from yourtable
See SQL Fiddle with Demo.
This will return the first 15 characters of the string and then concatenates the ...
to the end of it.
If you want to to make sure than strings less than 15 do not get the ...
then you can use:
select
case
when len(col)>=15
then left(col, 15) + '...'
else col end col
from yourtable
See SQL Fiddle with Demo
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