[Solved] Which statement about composite primary keys is TRUE? — Ans: They enforce uniqueness across the combination of columns | SQL

SQL - Table Constraints

Which statement about composite primary keys is TRUE?

AThey can consist of one or more columns

BThey allow NULL values in any of the key columns

CThey enforce uniqueness across the combination of columns

DThey automatically create foreign keys in other tables

Step-by-Step Solution

Solution:

Step 1: Check NULL allowance in primary keys
Primary keys do not allow NULL values in any column.
Step 2: Understand uniqueness enforcement
Composite primary keys enforce uniqueness across the combined columns, not individually.
Final Answer:
They enforce uniqueness across the combination of columns -> Option C
Quick Check:
Composite keys = Unique combination [OK]

Quick Trick: Composite keys enforce uniqueness on combined columns [OK]

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Which statement about composite primary keys is TRUE?