Nasdanika Models
SQL Model
Graphs
PrimaryKey
Attributes
InheritanceA primary key is a fundamental concept in relational databases — it uniquely identifies each record (row) in a table.
Key Characteristics of a Primary Key
- Uniqueness: No two rows can have the same primary key value.
- Non-nullable: Every row must have a value for the primary key; NULL is not allowed.
- Immutable (ideally): Primary key values should rarely change, as they anchor relationships across tables.