Getting this on a query.

You shouldn't use the variables scope in a function. Ideally, the variables in a function should be local to the function.

Pass variables as arguments instead. That way, any one can call the function, which can only be a good thing.

The functions createodbcdatetime and dateadd accept a date, not a string, as parameter. Hence the need to use parsedatetime to convert first from string to date object.

<cffunction access="public" name="qry_contestthisweek_get" output="false"  returntype="query">
<cfargument name="lastthursday" type="string" required="yes">
<cfargument name="datasource" type="string" required="yes">
<cfargument name="tablename" type="string" required="yes">

<!--- query name made local to this function --->

<cfset var qry_contestthisweek="">
<!--- convert string to date --->
<cfset lastThursdayDate = parseDatetime(arguments.lastthursday)>
<cfset nextThursdayDate = dateadd("d", 7, lastThursdayDate)>
<cfquery  name="qry_contestthisweek" datasource="#arguments.datasource#">   
    select    *      
    from     #arguments.tablename#
    where    1 = 1    
    and addeddate between <cfqueryparam  value="#createodbcdatetime(lastThursdayDate)#"  cfsqltype="CF_SQL_TIMESTAMP"> and <cfqueryparam  value="#createodbcdatetime(nextThursdayDate)#" cfsqltype="CF_SQL_TIMESTAMP"> 
    order by score, age    
</cfquery>
<cfreturn qry_contestthisweek>
</cffunction>