C# .NET - c# code for sql not in clause

i have a textbox where values are in the form like (2012,2013,2036).

i need to pass these textbox value in sql query like:

select *from stock where c_code not in ('"+textbox+"')

m getting error when i execute it.its showing cannot convert string to numeric (30,6).

Kindly help.

If c_code is a varchar/nvarchar type, you'll need to surround each item in the not in clause with a single quote.