Progress
Database Design
Guide
One-to-many Relationship
A one-to-many relationship exists when each row in one table has one or many related rows in a second table. Figure 2–4 shows some examples: one customer can place many orders. A sales representative can have many customer accounts.
Figure 2–4: Examples of a One-to-many Relationship
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However, the business rule may be that for one customer there may be zero-or-many orders, one student can take zero-or-many courses, and a sales representative may have zero-or-many customer accounts. This relationship is described as a zero-or-many relationship.
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