I am working in SQL Server 2008. I am trying to test whether a string (varchar) has only digit characters (0-9). I know that the IS_NUMERIC function can give spurious results.
I was attempting to find strings with numbers ONLY, no punctuation or anything else. I finally found an answer that would work here.
Using PATINDEX('%[^0-9]%', some_column) = 0 allowed me to filter out everything but actual number strings.