you can try something like
SELECT
Complete
,COUNT(0) AS cnt
FROM Documents
GROUP BY
Complete
ORDER BY 2 DESC
this will give you an idea of the values that might make sense as a where clause.
Taking your comment below into account, you can add
CASE WHEN Documents.Complete = 0 THEN 'pending'
WHEN Documents.Complete = 1 THEN 'has completed'
ELSE 'something strange happend'
END AS DocumentStatus
to your column list (and don't use the where clause). But from what you wrote I'm not sure what your desired output should look like.