Example of a data diagram for the Receipt Form and Subform The arrows show the Record Source for the Forms and the Control Source for the Combo Box. Before You Begin: Draw A Data Diagram Databases use a Form with a Subform to create a one-to-many relationship.   The Receipt Form has two Forms, two Tables, two Combo Boxes and three links. This is a good place to make a data diagram.   Form: Receipt Record Source: ReceiptSQ Default View: Form View Phone Combo: CustomerPhoneSQ   Form: ReceiptSubform Record Source: tblMovieRented Default View: Datasheet   Parent and Child Links: ReceiptID CustomerID DateRented