Candidate Key in Database
It is a minimal super. There can be multiple SQL candidate keys in a database relation and each.
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Suppose if ABC is a candidate key then neither A B C or any of its combination can be super key hence.
. A candidate key SQL is a column or a set of columns that can qualify as a primary key in the database. In other words it is any set of columns that have a unique combination of values in each row which makes it a superkey with the additional constraint that removing any column would possibly produce duplicate rows which makes it a minimal superkey. Candidate Key This is a set of columns or a single column which helps in uniquely recognizing any database.
For Example STUD_NO in STUDENT relation. A candidate key is a set of attributes or attribute which uniquely identify the tuples in relation or table. Suppose your system will have a table named User defined as below.
The rest of the attributes like SSN Passport_Number. A candidate key or simply a key of a relational database is a minimal superkey. In the EMPLOYEE table id is best suited for the primary key.
As we know that Primary key is a minimal super key so there is one. The candidate keys are as strong as the primary key. OR A minimal super key is called as.
Candidate Key is a Super Key whose no proper subset is a super key ie. A candidate key may be defined as- A set of minimal attribute s that can identify each tuple uniquely in the given relation is called as a candidate key. Basically candidate keys are a sub-set of Super keys.
The minimal set of attributes that can uniquely identify a tuple is known as a candidate key. Specific candidate keys are sometimes called primary keys secondary keys or alternate keys. A candidate key is a column or set of columns in a table that can uniquely identify any database record without referring to any other data.
A Candidate Key must uniquely identify each row in the table. Each table may have one or more candidate keys. Which contain only those attributes which are requiredneeded to uniquely identify tuples.
Definition of Candidate Key in DBMS. Candidate keys are selected from the set of super keys the only thing we take. These keys help us in.
All Candidate keys are Super keys. Candidate key is a concept that appears when you are designing a database system. Let us look at an example of a table where the Emp Id Mobile No and Email are the Candidate keys.
A super key with no redundant attribute is known as candidate key. The selection of any primary key depends on the developer and the specific needs.
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