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Non-prime attribute in DBMS?
Prime attribute are part of any candidate key. Non-prime attribute are not part of any candidate key.
What is a super key in DBMS?
A super key in a Database Management System (DBMS) is a set of one or more attributes that can uniquely identify a record in a table. It may include additional attributes beyond what is necessary for uniqueness, meaning it can be a broader category than a candidate key. While every candidate key is a super key, not all super keys are candidate keys. The primary purpose of a super key is to ensure that no two rows in a table have the same value for the attributes that make up the super key.
What is bcnf explain with respect to dbms?
Boyce -Codd normal form which is one of the forms of dbms noramlizations.normalization is converting the relations or tables in a standard form.bcnf is based on functional dependencies that take into account all candidate keys.a relation is in bcnf if every determinant has a candidate key..:)
What is the prime attribute in DBMS?
prime attributes are the attributes of a candidate key which will give uniqueness. a candidate key is (the subset of superkey) which gives uniqueness. Super key is the maximum set of attributes that can provide uniqueness example ABCDE is a super key AB CD DE are the candidate keys s.t. AB is the primary key. CD and DE are the secondary/alternate keys.
What is overlapping key DBMS?
Overlapping Key is a type of candidate key which occurs in BCNF (Boyce –Codd Normal Form).In the difference between 3NF and BCNF Example : A 3NF table which does not have multiple overlapping candidate keys is guaranteed to be in BCNF. Depending on what its functional dependencies are, a 3NF table with two or more overlapping candidate keys may or may not be in BCNF.
What ensures the value of the foreign key matches another tables primary key?
It is the DBMS that ensures the value of the foreign key matches another table's primary key when referential integrity constraints are enabled within the DBMS
Candidate key and primary key differnece?
All Primary keys are definitely Candidate Keys. A Candidate key is one which can be used as a Primary key that is not null and unique. That is one of the candidate keys can be chosen as a primary key.A Candidate key is a Unique Key and it can be used to find out any particular Tuple (row) in a table. The following are the differences between A Candidate key and a Primary Key: 1) A Unique key can be null but not a Primary key 2) On a table we can have only 1 primary key but 'N' number of unique keys.
How much types of keys are available in dbms?
There are five types of keys in database management system . The name of the five keys are as follows .:1) surrogate key -which is the system generated primary key .2) Primary key - same function as surrogate key but user defined.3) candidate key -combination of two more keys.4) alternate keys - alternative for candidate keys.5) foreign key - primary key of another table.There are five types of keys in database management system.These five keys are surrogate, primary, candidate, alternate, foreign keys .
What is the difference between primary key and candidate key?
Candidate Key is used to uniquely identify the records of a table. An attribute becomes a Primary Key, if all the other candidate keys lose race for being qualified as Primary Key.
Why do you designate one of the candidate key of relation to be the primary key?
We designate one of the candidate key of a relation to be a primary key because that primary key is use for any foreign key references.
What is secondary indexes in dbms?
secondary index is a key which is created other than primary key, to speed up processing.
Could DBMS being the key for the billionaires of the future?
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