[Solved] Which of the following is the correct syntax to add a foreign key constraint to an existing table? — Ans: ALTER TABLE Orders ADD FOREIGN KEY (CustomerID) REFERENCES... | SQL

SQL - Table Relationships

Which of the following is the correct syntax to add a foreign key constraint to an existing table?

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

BCREATE FOREIGN KEY Orders.CustomerID REFERENCES Customers(CustomerID);

CALTER TABLE Orders ADD PRIMARY KEY (CustomerID);

DADD FOREIGN KEY Orders.CustomerID TO Customers(CustomerID);

Step-by-Step Solution

Solution:

Step 1: Recall correct ALTER TABLE syntax for foreign keys
The correct syntax uses ALTER TABLE with ADD FOREIGN KEY and REFERENCES clauses.
Step 2: Check each option
ALTER TABLE Orders ADD FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID); matches the correct syntax. Options A, C, and D are incorrect or incomplete.
Final Answer:
ALTER TABLE Orders ADD FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID); -> Option A
Quick Check:
Correct foreign key syntax = ALTER TABLE Orders ADD FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID); [OK]

Quick Trick: Use ALTER TABLE ADD FOREIGN KEY with REFERENCES [OK]

Common Mistakes:

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Which of the following is the correct syntax to add a foreign key constraint to an existing table?