ocr: FORM RELHTIUNSHIP BETWEEN Form 1: Invoice IfF Form 1 is subform, hou: should Key field be updated uhen Main form Key is modified: Null Blank) - Form 2: Product If Form 2 is Subform, how should Key field be * updated when Nain form Key is modified: Restrict (Don't Update) BASED ON THE FOLLOWING FIELDS BEING EQUAL: Define at least one set) Field Product Code Product Code And Field And Field OPTIONAL RELHTIUNSHIP NAMES: (Form names are used as a default.) for Form 1: Form 2:Lookup Product Code Figure 4. Datatase maitans reterential integrity when detining the relationship between product and invo ...