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Super Key in RDBMS
Super Key is an attribute (or a set of attributes) that uniquely identify a tuple i.e. an entity in entity set.
It is a superset of Candidate Key, since Candidate Keys are selected from super key.
Example
Let us see an example −
<Student>
|
Student_ID |
Student_Enroll |
Student_Name |
Student_Email |
| S02 |
4545 |
Dave |
[email protected] |
| S34 |
4541 |
Jack |
[email protected] |
| S22 |
4555 |
Mark |
[email protected] |
The following are the super keys for the above table −
| {Student_ID} {Student_Enroll} {Student_Email} {Student_ID, Student_Enroll} {Studet_ID, Student_Name} {Student_ID, Student_Email} {Student_Name, Student_Enroll} {Student_ID, Student_Enroll, Student_Name} {Student_ID, Student_Enroll, Student_Email} {Student_ID, Student_Enroll, Student_Name, Student_Email} |
The following would be the candidate key from the above −
| {Student_ID} {Student_Enroll} {Student_Email} |
Updated on: 2020-06-15T13:46:26+05:30
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