SQL IsNumeric not working

Question

The reserve column is a varchar, to perform sums on it I want to cast it to a deciaml. But the SQL below gives me an error

select
cast(Reserve as decimal)
fr         


        

Answer 1

IsNumeric is possibly not ideal in your scenario as from the highlighted Note on this MSDN page it says "ISNUMERIC returns 1 for some characters that are not numbers, such as plus (+), minus (-), and valid currency symbols such as the dollar sign ($)."

Also there is a nice article here which further discusses ISNUMERIC.