ASP Classic Named Parameter in Paramaterized Query

问题:

I'm trying to write a parameterized query in ASP Classic, and it's starting to feel like i'm beating my head against a wall. I'm getting the following error:

Must declare the scalar variable "@something".

I would swear that is what the hello line does, but maybe i'm missing something...

<% OPTION EXPLICIT %>
<!-- #include file="../common/adovbs.inc" -->
<%

    Response.Buffer=false

    dim conn,connectionString,cmd,sql,rs,parm

    connectionString = "Provider=SQLOLEDB.1;Integrated Security=SSPI;Data Source=.\sqlexpress;Initial Catalog=stuff"
    set conn = server.CreateObject("adodb.connection")
    conn.Open(connectionString)

    set cmd = server.CreateObject("adodb.command")
    set cmd.ActiveConnection = conn
    cmd.CommandType = adCmdText
    cmd.CommandText = "select @something"
    cmd.NamedParameters = true
    cmd.Prepared = true
    set parm = cmd.CreateParameter("@something",advarchar,adParamInput,255,"Hello")
    call cmd.Parameters.append(parm)
    set rs = cmd.Execute
    if not rs.eof then
        Response.Write rs(0)
    end if


%>

回答1:

Here's some sample code from an MSDN Library article on preventing SQL injection attacks. I cannot find the original URL, but googling the title keywords (Preventing SQL Injections in ASP) should get you there quick enough. Hope this real-world example helps.

strCmd = "select title, description from books where author_name = ?"
Set objCommand.ActiveConnection = objConn
objCommand.CommandText = strCmd
objCommand.CommandType = adCmdText
Set param1 = objCommand.CreateParameter ("author", adWChar, adParamInput, 50)
param1.value = strAuthor
objCommand.Parameters.Append param1
Set objRS = objCommand.Execute()

See the following page on MSDN, near the bottom, referring specifically to named parameters.

MSDN example

回答2:

ADO is going to expect question marks instead of actual parameter names in this case. Right now, the SQL "select @something" is not actually parameterized: it sees the "@something" as an (undeclared) SQL variable, not as a parameter. Change your CommandText line to this:

cmd.CommandText = "select ?"

And I think you will get the result you are looking for.

Good luck!

回答3:

with server.createobject("adodb.command")
  .activeConnection = application("connection_string")
  .commandText = "update sometable set some_col=? where id=?"
  .execute , array(some_value, the_id)
end with

回答4:

I'm not sure what your query is intended to accomplish. I'm also not sure that parameters are allowed in the select list. MSDN used to have (many years ago, probably) a decent article on where parameters were allowed in a query, but I can't seem to find it now.

OTTOMH, your attempts to supply the parameter values to ADO look correct. Does your query execute if you do something like this?

SELECT 1 FROM sometable WHERE somefield = @something