Is the primary key field

In a relational database it is used as a way to uniquely identify a record in a table. It also allows tables within the database to reference the specific record within the table.

For example, a common practice is to have the database automatically determine the Primary Key with an auto-incrementing value starting at 1 upon inserting each new record.

The reason for uniquely identifying the record is there could be cases where the data between two records are exactly the same, but they need to be separate as they do represent different things.

For example, let's say you have a database containing the name of a person "John Smith". What would happen if you added "John Smith" into the database multiple times without a Primary Key? By providing the Primary Key as shown below, you can now reference the correct "John Smith".

Id Name

1 John Smith

2 John Smith