One to Many Links
In a one-to-many link, one record in the parent table can match several record in the child table (e.g. one manufacturer to many products, one department to many employees, or one invoice to many purchased items). The following example links all product records that are associated with a particular vendor record.
The records are linked to the VEND_ID field as follows. Picture
Child records in linked sets that do not match any parent table records do not appear in a query. A child record can be the child of more than one parent record. This often occurs when the child table is a lookup table used for reference. For example, in the Invoice set, a particular product record matches more than one Invoice item record, since the product can be ordered on several invoices.