[Solved] You wrote this SQL to create a one-to-many relationship:CREATE TABLE Orders (OrderID INT PRIMARY KEY, CustomerID INT, FOREIGN KEY (CustomerID) REFERENCES... What is the most likely cause? | SQL

SQL - Table Relationships

You wrote this SQL to create a one-to-many relationship:

CREATE TABLE Orders (OrderID INT PRIMARY KEY, CustomerID INT, FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID));

But you get an error. What is the most likely cause?

AOrderID should not be primary key in Orders

BCustomers table does not exist or CustomerID is not a primary key

CForeign key should be in Customers table, not Orders

DCustomerID column type must be VARCHAR, not INT

Step-by-Step Solution

Solution:

Step 1: Check foreign key reference validity
Foreign key must reference an existing table and a primary or unique key column.
Step 2: Verify Customers table and CustomerID key
If Customers table or CustomerID primary key is missing, error occurs.
Final Answer:
Customers table does not exist or CustomerID is not a primary key -> Option B
Quick Check:
Foreign key references must exist and be keys [OK]

Quick Trick: Foreign key target must exist and be primary/unique key [OK]

Common Mistakes:

MISTAKES

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