In an RDBMS, which of the following keys is restricted to a single occurrence…
2026
In an RDBMS, which of the following keys is restricted to a single occurrence per table?
- A.
Alternate Key
- B.
Candidate Key
- C.
Foreign Key
- D.
Primary Key
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Correct answer: D
The correct answer is Primary Key.
In an RDBMS, a primary key uniquely identifies each record in a table. Each table can have only one primary key, although it may consist of one or more columns (composite key). This restriction ensures entity integrity and prevents duplicate or NULL values in the key field.
Thus, only one primary key is allowed per table.