isNumeric() - it can not be right?

If you use the ISNUMERIC function to determine if a value is numeric you might be in for a surprise
Run the 3 lines of code below and you will see what I mean

DECLARE @S VARCHAR(50)
SET @S = CHAR(9) @S NOW CONTAINS THE TAB CHARACTER
SELECT ISNUMERIC(@S), ISNUMERIC(CHAR(9)),ISNUMERIC('1D2'),ISNUMERIC('D')

As you can see TAB is returned as numeric as well the value 1D2
A better way to test for this would be with LIKE and %[a-z]%
If you run the example below you will see that the select statement with the ISNUMERIC function or LIKE returns one row more than the statement with LIKE and ISNUMERIC combined

CREATE TABLE #foo (Value VARCHAR(20))
INSERT INTO #foo
SELECT '1' UNION ALL
SELECT '3' UNION ALL
SELECT 'B' UNION ALL
SELECT '2' UNION ALL
SELECT '33.331' UNION ALL
SELECT 'adad1' UNION ALL
SELECT '1d2' UNION ALL
SELECT '^' UNION ALL
SELECT '17777.999'

--returns ^
SELECT * FROM #foo
WHERE Value NOT LIKE '%[a-z]%'

--returns 1d2
SELECT * FROM #foo
WHERE ISNUMERIC(Value) = 1

--returns correct result
SELECT * FROM #foo
WHERE Value NOT LIKE '%[a-z]%'
AND ISNUMERIC(Value) = 1

Denis the SQL Menace

http://sqlservercode.blogspot.com/

i suppose it makes more sense to use a function to encasulate the logic for this check.
however, it seems absurd to have a function in mssql 200 that does not do what it was supposed to do.

what a shame..

thanks for your help Jens!

regards,

nicolas