IsNumeric function

The function returns 1 for numeric values, and 0 for non-numeric values.

CREATE TABLE #CustomerNames
(
	CustomerId int,
	CustomerName varchar(25)
)	

INSERT INTO #CustomerNames
SELECT 1, 'Bob Johnson'
UNION ALL
SELECT 2, 'Al Riley'
UNION ALL
SELECT 3, 'Mike Henry'

SELECT ISNUMERIC(CustomerID), ISNUMERIC(CustomerName) FROM #CustomerNames

Results
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1     0