Surrogate Key means
-
It is a primary key for a Dimension table.
-
It is a system generated sequence numbers
-
It is a unique key
-
It is a foreign key for a FACT table.
Surrogate keys are system-generated sequence numbers used as primary keys when natural keys don't exist. They're not foreign keys, dimension keys by definition, or necessarily unique (surrogate keys are always unique by design).
To answer this question, let's go through each option to understand why it is correct or incorrect:
Option A) It is a primary key for a Dimension table - This option is incorrect. A surrogate key is not specifically a primary key for a Dimension table. It can be used as a primary key, but it is not limited to that role.
Option B) It is a system-generated sequence number - This option is correct. A surrogate key is a unique identifier that is generated by the system, typically using a sequence number or an auto-incrementing value. It is used to uniquely identify records in a table and is not derived from any meaningful data.
Option C) It is a unique key - This option is partially correct. A surrogate key is indeed a unique key, but its uniqueness is achieved by being generated by the system rather than being inherently unique based on the data it represents.
Option D) It is a foreign key for a FACT table - This option is incorrect. A surrogate key is not specifically a foreign key for a FACT table. While it can be used as a foreign key, it is not limited to that role.
The correct answer is B) It is a system-generated sequence number. This option is correct because a surrogate key is a unique identifier generated by the system, typically using a sequence number or an auto-incrementing value, to uniquely identify records in a table.