Column selectivity (SQL Server 2k8)

I use this snippet frequently when I have to implement indices for new queries on production servers. It helps decide index column order (wherever it is a question, of course).

Code:

DECLARE @total_unique FLOAT = 0
DECLARE @total_rows FLOAT = 0

$$DECLARE @targy VARCHAR(256) = '$OBJECT$', @sema VARCHAR(256), @tabla VARCHAR(256), @mezo VARCHAR(256)
IF PARSENAME(@targy,3) IS NULL SELECT @sema = PARSENAME(@targy,2), @tabla = PARSENAME(@targy,1) ELSE SELECT @sema = PARSENAME(@targy,3), @tabla = PARSENAME(@targy,2), @mezo = PARSENAME(@targy,1)
DECLARE @sql VARCHAR(max)

SELECT @sql = '
SELECT @total_unique = (
   SELECT COUNT(1)
   FROM (
         SELECT DISTINCT
            t' + ISNULL('.' + @mezo,'') + '
         FROM ' + @sema + '.' + @tabla + ' AS t
      ) AS a
)

SELECT @total_rows = (
   SELECT COUNT(*)
   FROM ' + @sema + '.' + @tabla + ' AS t
)
-- selectivity ratio for a specific column
SELECT ROUND(@total_unique/@total_rows,2,2) AS ''Selectivity ratio'', @total_unique AS ''Total unique'', @total_rows AS ''Total rows'' '

SELECT @sql
$$