mssql convert varchar to float
sql-server, type-conversion
Solution
You can convert varchars to floats, and you can do it in the manner you have expressed. Your varchar must not be a numeric value. There must be something else in it. You can use IsNumeric to test it. See this:
declare @thing varchar(100)
select @thing = '122.332'
--This returns 1 since it is numeric.
select isnumeric(@thing)
--This converts just fine.
select convert(float,@thing)
select @thing = '122.332.'
--This returns 0 since it is not numeric.
select isnumeric(@thing)
--This convert throws.
select convert(float,@thing)
Problem
I have a field value productlength of 0.123. This is from a view and has a data type of varchar. I need to convert it to a float or numeric value so as o perform math comparisons. convert(float,productlength) and cast(productlength as float) both do not work. `error varchar cant be converted to float` or somethiing liek that. From what I have read varchar can simply not be converted to a numeric string? Any clever ways around this?