Question

A key that creates a relationship between two tables is called a ____ key.

• A. Foreign
• B. Primary
• C. Unique
• D. Join

Hint:

Remember:
• Primary Key = Uniquely identifies a record.
• Foreign Key = Connects two related tables.
• One table's Primary Key becomes another table's Foreign Key.

Answer 1

The Correct Option is A

Concept: A Foreign Key is a field (or set of fields) in one table that refers to the Primary Key of another table. It establishes a relationship between the two tables and helps maintain referential integrity.
• Connects related tables.
• References the Primary Key of another table.
• Prevents invalid or orphan records.

Step 1: Understand Primary Key and Foreign Key.

• Primary Key uniquely identifies each record in a table.
• Foreign Key refers to the Primary Key of another table. Thus, the relationship between two tables is established using a: \[ \boxed{\text{Foreign Key}} \]

Step 2: Example of a Foreign Key.
Suppose there are two tables: Student Table {|c|c|} StudentID (Primary Key) & Name
101 & Rahul
102 & Priya
Marks Table {|c|c|} StudentID (Foreign Key) & Marks
101 & 92
102 & 88
Here, StudentID in the Marks table is a Foreign Key because it refers to the Primary Key in the Student table.

Step 3: Analyse the options.

• Foreign Key -- Creates relationships between tables. (Correct)
• Primary Key -- Uniquely identifies records within the same table.
• Unique Key -- Ensures unique values but does not establish relationships.
• Join -- SQL operation used to retrieve data from related tables, not a key.

Step 4: Final conclusion.
Hence, the key used to establish a relationship between two tables is the: \[ \boxed{\text{Foreign Key}} \]