不从ASP Classic中存储的proc中捕获返回值

Question

Sorry for the long post but I wanted to include all details.

I have a JavaScript function using ajax that calls some asp code which in turn calls a stored procedure to simply check if a record already exists. If it does exist one image appears, if it doesn't exist a different image appears. For some reason I am unable to capture the results in my asp variable, it returns empty, which makes the call always returns false. I have tested the SQL procedure by itself and it works so the data is there. Here is the code which will explain better.

Stored Proc:

ALTER PROCEDURE [dbo].[UserName_Get] 
    -- Add the parameters for the stored procedure here
    @UserName nvarchar(50)
    ,@FacilityID INT
    ,@UserNameExists INT OUT
AS

BEGIN
    SELECT @UserNameExists= ISNULL((SELECT UserID FROM MyTable WHERE FacilityID = @FacilityID AND Username = @UserName),0)

END

Classic ASP code:

<% Response.Buffer = True %>
<!-- #include file="../../_app_init.asp" -->

<%
Dim action, p_UserName
action = SqlSanitizeStr(trim(request("action")))
'dim UserNameExists

If action = "CheckUserName" Then
    ' Check to see if this username already exists for this facility
    ' This is an Ajax routine to check if the username already exists at the current facility or not. Returns "False" if UserName does not exist.

    p_UserName=SqlSanitizeStr(trim(request("UserName")))


    Set objCmd = Server.CreateObject("ADODB.Command")
    Set objCmd.ActiveConnection = DB_CONN
    objCmd.CommandText = "UserName_Get"
    objCmd.CommandType = adCmdStoredProc
    objCmd.Parameters.Append objCmd.CreateParameter("@UserName",        adLongVarChar,      adParamInput,   50        , p_UserName)
    objCmd.Parameters.Append objCmd.CreateParameter("@FacilityID",      adInteger,      adParamInput,           ,   LOGIN_FACILITY_ID)
    objCmd.Parameters.Append objCmd.CreateParameter("@UserNameExists",      adInteger,      adParamReturnValue)
    objCmd.Execute ,, adExecuteNoRecords
    UserNameExists = objCmd.Parameters("@UserNameExists").Value ' Get value of output parameter



    If UserNameExists>0 Then

        Response.Write ("True")

    Else
        Response.Write ("False")

    End If

End If



%>

JavaScript Ajax Call

<script type="text/javascript">


  function CheckUserName(UserName_element) {


    var UserName = UserName_element.value;
    var valid_UserName_image = document.getElementById('valid_UserName_image');
    var invalid_UserName_image = document.getElementById('invalid_UserName_image');

    $j.ajax({
        data: { action: 'CheckUserName', p_UserName: UserName },
        type: 'GET',
        url: 'page_logic/_check_username_ajax.asp',
        success: function (result) {

            //Just to see what the return value is
            alert(result)

            if (result == "True") {


                valid_UserName_image.style.display = "none";
                invalid_UserName_image.style.display = "inline";

            }
            else {

                valid_UserName_image.style.display = "inline";
                invalid_UserName_image.style.display = "none";

                }

            }
        }
    );

}


</script>

I put in alert(result) to see what was being returned, it is always empty.

If I change the stored proc to simply

 SELECT @UserNameExists=0 or SELECT @UserNameExists=1

It will return a value, but of course that is hard coding the result and not actually getting records from the DB.

Answer 1

The issue is the mix up between the use of OUTPUT and RETURN in stored procedures in SQL Server.

To clear things up, your stored procedure is expecting an OUTPUT parameter instead of a RETURN value which is something different.

Try changing your output parameter statement to;

objCmd.Parameters.Append objCmd.CreateParameter("@UserNameExists", adInteger, adParamOutput)

For reference adParamReturnValue is used to return the value of the RETURN statement if used and is limited to INT values.