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Difference between partial dependency and fully functional dependency?
The difference is that partial dependency is when a database's attribute is only partially dependent on the primary key. Fully functional dependency is when the attribute is entirely dependent on the key.
What is Partial functional dependency?
Partial Functional Dependency Indicates that if A and B are attributes of a table , B is partially dependent on A if there is some attribute that can be removed from A and yet the dependency still holds. Say for Ex, consider the following functional dependency that exists in the Tbl_Staff table: StaffID,Name -------> BranchID BranchID is functionally dependent on a subset of A (StaffID,Name), namely StaffID. Source :http://www.mahipalreddy.com/dbdesign/dbqa.htm
How functional dependency is related to database table design?
The functional dependency is related to the database table design through the foreign and primary keys. The foreign and primary keys are functionally dependent on each other.
Why relations should not have transitive dependency Illustrate with example?
Relations should not have transitive dependencies because they can lead to data anomalies, redundancy, and inconsistency. For example, consider a relation where we have attributes: StudentID, Course, and Instructor. If StudentID determines Course, and Course determines Instructor, then StudentID indirectly determines Instructor. This transitive dependency can cause issues such as update anomalies; if an instructor changes, we must update every record for that course, risking inconsistencies if some records are missed. To resolve this, we can normalize the relation to eliminate transitive dependencies, ensuring data integrity.
What is transitive dependency in normalization?
Transitive dependency in database normalization refers to a situation where a non-key attribute depends on another non-key attribute rather than directly depending on the primary key. This can lead to redundancy and anomalies during data manipulation. To eliminate transitive dependencies, a database is typically decomposed into multiple tables, ensuring that each non-key attribute is functionally dependent only on the primary key. This is a key consideration when moving a database schema into Third Normal Form (3NF).
What is non trivial functional dependency?
-->non trivial functional dependency is totally opposite to the trivial functional dependency. --> non trivial dependency means X-->Y that is if Y is not proper subset of X table or relation with X then it said to be non trivial functional dependency.
What is transitive dependency?
Transitive dependencies occur when a determinant affects the values of more than one business object.
What is data dependency in DBMS?
Data dependency in DBMS refers to the relationship between different data elements within a database. There are three main types: functional dependency (one attribute determines another), partial dependency (part of a composite key determines other attributes), and transitive dependency (dependency between non-key attributes). Understanding data dependencies is crucial for database normalization and maintaining data integrity.
What is functional dependency in oracle?
In Oracle, functional dependency is when the value of one thing is completely determined by another thing. Functional dependency happens when one attribute determines another attribute in a relation.
Describe the purpose of normalizing data and also list out the dependencies involved in the process of normalization?
The purpose of normalizing data in DBMS is to reduce the data redundancy and increase the consistency of data. a) Partial dependency: non-prime attribute ( field) depends on other non-prime attributes b) Functional dependency c) Transitive dependency
Difference between partial dependency and fully functional dependency?
The difference is that partial dependency is when a database's attribute is only partially dependent on the primary key. Fully functional dependency is when the attribute is entirely dependent on the key.
What is Trivial and Non Trivial Dependency?
Trivial functional dependencyA trivial functional dependency is a functional dependency of an attribute on a superset of itself. {Employee ID, Employee Address} → {Employee Address} is trivial, as is {Employee Address} → {Employee Address}.
What is difference between Partial Functional Dependency and Full Functional Dependency?
A functional dependency is defined as a constraint between two sets of attributes in a relation from a database.Given a relation R, a set of attributes X in R is said to functionally determine another attribute Y, also in R, (written X→ Y) if and only if eachX value is associated with at most oneY value.A functional dependency X --> Y is full functional dependency if removal of any attribute 'k' from X means that the dependency does not hold any more. Full functional dependency is minimal in size.Partial Functional Dependency Indicates that if A and B are attributes of a table, B is partially dependent on A if there is some attribute that can be removed from A and yet the dependency still holds.A key is a set of attributes that uniquely identifies an entire tuple, a function dependency allow us to express constraints that uniquely identify the values of certain attribute.
Fully functional dependency?
A functional dependency X --> Y is full functional dependency if removal of any attribute 'k' from X means that the dependency does not hold any more.Full functional dependency is minimal in size (contain non-redundant data)In a relation R , attribute B of R is fully functionallydependent on an attribute or set of attributes A of R , if B is functionally dependent on A, but not functionally dependent on any proper subset of A.ORAàB is a fully functionally dependency, if removal of any attribute X from A would result into the cancellation of dependency. i.e. (A-{X})-->B does not hold.
Is every FD is MVD?
Not necessarily. While every functional dependency (FD) implies a multivalued dependency (MVD), not every MVD is a functional dependency. MVDs involve more complex relationships between attributes compared to FDs.
A condition in which one attribute is dependent on another attribute when neither attribute is part of the primary key?
transitive dependency
What is non transitive dependency?
Non-transitive dependency occurs in a database when a relationship between three or more attributes does not imply a direct relationship between all of them. Specifically, if attribute A is dependent on attribute B, and attribute B is dependent on attribute C, it does not necessarily mean that attribute A is dependent on attribute C. This type of dependency can complicate database normalization and design, as it can lead to redundancy and anomalies in data management. Understanding non-transitive dependencies is crucial for ensuring data integrity in relational databases.
