Another way that you can use is a query like this:
SELECT DISTINCT
LTRIM(m.n.value('.[1]','varchar(8000)')) as columnName
FROM
(SELECT CAST('' + REPLACE(t.val,',','') + '' AS XML) AS x
FROM (SELECT '1, 1, 1, 2, 5, 1, 6') AS t(val)
) dt
CROSS APPLY
x.nodes('/XMLRoot/RowData') m(n);