Like this:

CREATE FUNCTION [dbo].[ifn_NumOccurrences]

(

@sourceString varchar(1000),

@searchString varchar(10)

)

RETURNS TABLE

AS

return

SELECT numTimes = (DATALENGTH(@sourceString) - DATALENGTH(REPLACE(@sourceString COLLATE Latin1_General_BIN2, @searchString, ''))) / DATALENGTH(@searchString);

GO