Error trapping for ASP, Coldfusion, ASP.NET
ASP Classic
Error trapping in ASP Classic is poor, you just count with on error resume next, on error goto 0 and the err object.

<% Set cn = Server.CreateObject("ADODB.Connection")
cn.Open "data source name", "userid", "password"
'turn on error trapping on error resume next 'execute the code you want to check for error cn.Execute "some insert/update/delete SQL sentence"
'check for errors if err.number <> 0 then response.write "There was an error code " & err.number & " and description " & err.description end if 'turn error trapping off on error goto 0 %>

Source and more information at Microsoft: Error handling sample from ASP101