# Foreign Key
A Foreign key is a [[Constraint]] that protects links between tables. Foreign key is a attribute or attributes that link to the [[Primary Key]] of a other entity set (table).

## Example

|ID (PK)|Name|Age|Sex|Length|
|-----|-----|-----|-----|-----|
|1|Nick|21|M|190|

|ID (PK)|Job|Age|Sex|Length|
|-----|-----|-----|-----|-----|
|1|Nick|21|M|190|