The attribute ClientID in the Orders table would be considered

Question

BlackTom AI · Accepted Answer

ClientID is a foreign key in the Orders table because it references the primary key of the Clients entity to link each order to the client who placed it.

1) Relevant concepts:
- Entity: a real-world object represented by a table (e.g., Clients, Orders).
- Attribute: a column or property of an entity (e.g., LastName, OrderDate).
- Primary key (PK): an attribute or set of attributes that uniquely identifies a row in its own table (e.g., ClientID in Clients or OrderNumber in Orders).
- Foreign key (FK): an attribute in one table that stores the primary key value of another table to create a relationship and enforce referential integrity.

2) Step-by-step reasoning:
- The diagram shows Clients as an entity with ClientID as an attribute (underlined in the Clients box, indicating it is the Clients table primary key).
- Orders is another entity with its own attributes (OrderNumber is likely the PK for Orders).
- The relationship diamond “Places” between Clients and Orders is labeled 1 on the Clients side and N on the Orders side, meaning one client can place many orders (1:N).
- To implement a 1:N relationship in a relational schema, the PK from the “one” side (Clients.ClientID) is added to the “many” side (Orders) as a foreign key.
- Therefore ClientID appears in Orders not to uniquely identify orders (it doesn’t guarantee uniqueness there) but to reference which client made each order.

3) Why the correct option is correct:
- ClientID in Orders stores the key of the referenced Clients row, so it is a foreign key enforcing the relationship.

4) Why other options are incorrect:
- a. “a relationship” — the relationship is represented by the diamond (Places), not an attribute.
- b. “a primary key” — ClientID is the PK of Clients, but in Orders it is not the primary key (OrderNumber is).
- c. “an entity” — ClientID is an attribute/column, not an entity.

Conclusion: The correct choice is d. a foreign key. This matches the provided answer.

The attribute ClientID in the Orders table would be considered单项选择题

类似问题

Following are the definitions of 2 tables in a DBMS: EMPLOYEE(EmpID,FirstName,LastName,PositionID,Salary) POSITION(PositionID,PositionName,DeptID,EmplID) What is the foreign key in the Table EMPLOYEE?

Question 15

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