Difference Between Super key and Candidate Key in SQL

Google Advertisements

Difference Between File System and DBMS Difference Between Primary and Foreign Key

Difference Between Candidate Key and Super key in SQL

A DBMS key is an attribute or set of an attribute which helps you to identify a row(tuple) in a relation(table).

Super key is any combination of columns which uniquely identify a row in the table. Candidate key is minimal super key from which you cannot remove any fields else it will not be able to uniqule identify the rows. We can say that candidate key is the proper subset of super key

Employee Table

Let's take example of an Employee table:
Employee (
Employee ID,
FullName,
SSN,
DeptID
)

Here Candidate Key: are individual columns in a table that qualifies for uniqueness of all the rows. Here in Employee table EmployeeID & SSN are Candidate keys.

And Super Key: If you add any other column/attribute to a Primary Key then it become a super key, like EmployeeID + FullName is a Super Key.

Difference Between Candidate Key and Super key in SQL

Candidate KeySuper Key
It can be a column or combination of columns which can be qualify as Unique key. A table can have more than one candidate key, but only one candidate key can be primary key.A super key is a set or one of more columns to uniquely identify rows in a table.
Candidate key is minimal super key from which you cannot remove any fields else it will not be able to uniqule identify the rows. We can say that candidate key is the proper subset of super key.Super key is any combination of columns which uniquely identify a row in the table.
While in a relation, number of candidate keys are less than number of super keysIn a relation, number of super keys are more than number of candidate keys
dddLanguageDMLionanguage
Candidate key's attributes can also contain NULL valuesSuper key's attributes can contain NULL values
Candidate Key is a proper subset of a super key.Super Key is an attribute (or set of attributes) that is used to uniquely identifies all attributes in a relation.
All candidate keys are super keys.All super keys can't be candidate keys
Various candidate keys together makes the criteria to select the primary keys.Various super keys together makes the criteria to select the candidate keys
difference between super key and condidate key
Difference Between File System and DBMS Difference Between Primary and Foreign Key

Google Advertisements

We have more than 5 Groups which have 500000+ Members and some Pages have more than 100000+ members. For Advertisement contact on [email protected] or 8076671483

Buy This Ad Space @$50 per Month, Ad Size 600X200 Contact on: [email protected] or 8076671483

Pure VPN Privide Lowest Price VPN Just @ $1.65. Per Month with Non Detected IP Lowest Price Non Detected IP VPN

Classpath variable is set for providing a path for predefined Java classes which is used in our application. All classes are available in lib/rt.jar so we set classpath upto lib/rt.jar. Difference between path and classpath in Java

Cloud computing is the on demand availability of computer system resources, especially data storage and computing power, without direct active management by the user. Cloud Computing Tutorial

College Projects Related to Java, AWT, C Projects for College, C++ Projects for College, Android Projects. Download Java C C++ Projects

Download Projects

Adsense Advertisements


Buy This ads Space 8076671483

Buy This Ad Space @$120 per Month, Ad Size 300X600 Contact on: [email protected] or 8076671483 Try this Keyword C++ Programs