[Solved] Which SQL statement correctly defines a foreign key with referential integrity enforcement? — Ans: ALTER TABLE Orders ADD FOREIGN KEY (CustomerID) REFERENCES... | SQL

SQL - Table Relationships

Which SQL statement correctly defines a foreign key with referential integrity enforcement?

AINSERT INTO Orders (OrderID, CustomerID) VALUES (1, 100);

BCREATE TABLE Orders (OrderID INT, CustomerID INT PRIMARY KEY);

CALTER TABLE Orders ADD FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID);

DSELECT * FROM Orders WHERE CustomerID = Customers.CustomerID;

Step-by-Step Solution

Solution:

Step 1: Identify foreign key syntax
The correct syntax to add a foreign key is using ALTER TABLE with ADD FOREIGN KEY referencing another table's column.
Step 2: Check each option
ALTER TABLE Orders ADD FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID); correctly adds a foreign key constraint. CREATE TABLE Orders (OrderID INT, CustomerID INT PRIMARY KEY); wrongly sets CustomerID as primary key without foreign key. INSERT INTO Orders (OrderID, CustomerID) VALUES (1, 100); is an insert, not a constraint. SELECT * FROM Orders WHERE CustomerID = Customers.CustomerID; is a select query, not a constraint definition.
Final Answer:
ALTER TABLE Orders ADD FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID); -> Option C
Quick Check:
Foreign key syntax = ALTER TABLE Orders ADD FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID); [OK]

Quick Trick: Foreign keys use ALTER TABLE ADD FOREIGN KEY ... REFERENCES [OK]

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Which SQL statement correctly defines a foreign key with referential integrity enforcement?