What is the difference between a primary key and a surrogate key?

Question

I googled a lot, but I did not find the exact straight forward answer with an example.

Any example for this would be more helpful.

Answer 1

A surrogate key is a made up value with the sole purpose of uniquely identifying a row. Usually, this is represented by an auto incrementing ID.

Example code:

CREATE TABLE Example
(
    SurrogateKey INT IDENTITY(1,1) -- A surrogate key that increments automatically
)

A primary key is the identifying column or set of columns of a table. Can be surrogate key or any other unique combination of columns (for example a compound key). MUST be unique for any row and cannot be NULL.

Example code:

CREATE TABLE Example
(
    PrimaryKey INT PRIMARY KEY -- A primary key is just an unique identifier
)