operation in 2 tables

hello.

i have 2 tables :

1. marks

2. grad

let say i have column pointValue for the grad and i want to use it, how do we retrieve it from the database..

im trying this :

<cfif qd.marks GTE qGetGrade.to_kysMark>
    <cfset value= qGetGrade.Point_value>   
    <cfset total_value = total_value + value>

</cfif>

but the result unfavorable.. any suggestion? thanks