using "on error resume next" in classic ASP, and how to handle errors

Question

Good day all, I would like to ask a thing about on error resume next

let's assume we have a loop to navigate through a recordset like:

Do while not rs.EOF
query = "UPDATE ...."    
conn.execute(query)    
rs.movenext
loop

i would like to be sure the UPDATE is going good, and i would like to check if there is some problems, so I have put a debugging features in the code like:

Do while not rs.EOF
query = "UPDATE ...."

on error resume next

conn.execute(query) 

If Err.Number <> 0 Then
   Response.write(Err.Number)
   response.write("<br>")
   response.write(Err.description)
   response.write("<br>")
   response.write(query)
   response.write("<br><br>")
end if

on error goto 0

rs.movenext
loop

the question is : during a loop, if it encounters an error, the next cycle will the error be there (and so triggers again the error block) ? or on error goto 0 will clear the Err object? in other words, will it works as a error handling?

Answer 1

VBScript resets the error on goto 0:

on error resume next
i = 1 / 0
WScript.echo( err.number ) '' prints 11 (div by 0)
on error goto 0
WScript.echo( err.number ) '' prints 0 (no error)

There is also the explicit err.clear().

Answer 2

The correct code to use is

Err.Clear

I have tested it with the following code

<%on error resume next
   response.write (p(10))
   Response.write(Err.Number)
   response.write("<br>")
   response.write(Err.description)
   response.write("<br>")
   Err.Clear
   Response.write(Err.Number)
   response.write("<br>")
   response.write(Err.description)
   response.write("<br>")



%>

And you can see the correct response is below, which shows the error being cleared

*13

Type mismatch

0*

Answer 3

on error resume next statement just only ignore the current line error and send the program control to the next line.

on error goto 0 just stops the working of on error resume next.That's it.

<%
on error resume next
response.write(1/0)
if err.number <> 0 then
response.write("<b>" & "err= "&"</b>")
response.write(err.description)
response.write("<b>" & " err number= "&"</b>" )
response.write(err.number&"</br>")
end if
'after this statement ASP will no longer resume the error and program terminate at here if error occur after this line
on error goto 0
response.write(6/0)
%>