-->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.
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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.
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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.
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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}.
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A functional dependency X->Y is transitive in R, if there exists an attribute Z in R, such that X-> Z, Z-> Y .
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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.
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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.
OR
AàB 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.
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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.
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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
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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.
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In DBMS there is three type of functional dependency
1 FULL FUNCTION DEPENDENCY.
2 PARTIALLY FUNCTION DEPENDENCY.
3 TRACIENT FUNCTION DEPENDENCY.
Functional Dependency can be classified as follows:
Full Functional dependency Indicates that if A and B are attributes(columns)of a table, B is fully functionally dependent on A if B is functionally dependent on A ,but not on any proper subset of A.
Partial Functional Dependency Indicates that if Aand 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.
Transitive Functional Dependency: A condition where A , B and C are attributes of a table such that if A is functionally dependent on B and Bis functionally dependent on C then C is Transitively dependent on A via B
For Detailed explanation with example visit Authors original Posting
http://www.mahipalreddy.com/dbdesign/dbqa.htm
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A dependency diagram is a visual representation of a dependency graph. Dependency diagrams are integral to software development, outlining the complex, interrelationships of various functional elements. Typically in a dependency diagram, arrows point from each module to other modules which they are dependent upon.The dependency diagram is used as an aid to normalization within database design.
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A constraint between two sets of attributes is known as functional dependency in relational database. Determination of functional dependencies is vital in database denormalization, normalization and relational model.
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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.
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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.
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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
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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
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Functional Dependencies A Functional Dependency describes a relationship between attributes in a single relation. An attribute is functionally dependant on another if we can use the value of one attribute to determine the value of another. Example: Employee_Name is functionally dependant on Social_Security_Number because Social_Security_Number can be used to determine the value of Employee_Name. We use the symbol -> to indicate a functional dependency. -> is read functionally determines Student_ID -> Student_Major Student_ID, Course#, Semester# -> Grade SKU -> Compact_Disk_Title, Artist Model, Options, Tax -> Car_Price Course_Number, Section -> Professor, Classroom, Number of Students The attributes listed on the left hand side of the -> are called determinants. One can read A -> B as, "A determines B".
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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
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Normalization is a process to reduce the redundancy by removing function dependencies BCNF (Boyece code normal form) has all functional dependencies A to B are trivial of discriminator should be superkey. To get relation in BCNF, Splitting the relation schema not neccessarily preserve all functional dependency, Loss less decomposition and dependency are main points for the normalization sometime, it is not possible to get a BCNF decomposition that is dependency, preserving. While 4NF has very similar definition as BCNF. A relational Schema is in 4NF, if all multivalued dependencies A to B are trivial and determinate A is superkey of schema. If a relational schema is in 4nf, it is already in BCNF. and 4NF decomposition preserve the all functional dependency. so 4NF is preferable than to have BCNF.
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a functionaly dependency is an association between two relational attribute of same relational database.one of the attribute is known as determinant and the other one is determined.for the each value of determinant there is only one value associated of determined.
graphicaly it can be represented A----->B .
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If the radius is larger, the surface will also be larger. As a functional dependency, you only need one - the radius, or the surface - whatever.
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A functional Dependency_theory_(database_theory)(FD) is a constraint between two sets of attributes in a Relational_modelfrom a Database
Given a relation R, a set of Attribute_(computing) X in R is said to functionally determineanother attribute Y, also in R, (written X → Y) if and only if each X value is associated with precisely one Y value. Customarily we call X the determinant set and Y the dependent attribute. Thus, given a Tupleand the values of the attributes in X, one can determine the corresponding value of the Y attribute. For the purposes of simplicity, given that X and Y are sets of attributes in R, X → Y denotes that X functionally determines each of the members of Y - in this case Yis known as the dependent set. Thus, a Candidate_keyis a minimal set of attributes that functionally determine all of the attributes in a relation.(Note: the "function" being discussed in "functional dependency" is the function of Identification_(information).)
A functional dependency FD: X → Y is called trivial if Y is a Subsetof X.
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A DEPENDENCY X->Y IS SAID TO BE TRIVIAL DEPENDENCY IF Y IS A PROPER SUBSET OF X OTHERWISE NON TRIVIAL DEPENDENCY.
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A DEPENDENCY X->Y IS SAID TO BE TRIVIAL DEPENDENCY IF Y IS A PROPER SUBSET OF X OTHERWISE NON TRIVIAL DEPENDENCY.
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Found a nice explanation here:
http://www.e-consultancy.com/knowledge/glossary/1163/partial-functional-dependency.html In database terminology, a partial functional dependency occurs when the value in a non-key attribute of a table is dependent on the value of some part of the table's primary key (but not all of it).
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Full Dependency:
Given a relation R and functional dependency x->y (y is fully functionally dependent on x)there is no any z->y ,where Z is a proper subset of x
Partial Dependency:
If any proper subset of the key determine any of the non-key attributes then there exist a partial dependency p q->c d (p q is the primary key)
p->c
q->c
p->d
q->d
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A DEPENDENCY X->Y IS SAID TO BE TRIVIAL DEPENDENCY IF Y IS A PROPER SUBSET OF X OTHERWISE NON TRIVIAL DEPENDENCY.
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The area of Ross Dependency is 450,000 square kilometers.
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The duration of Sexual Dependency - film - is 1.75 hours.
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There are a few locations of chemical dependency treatment centers in the US. These include: Crouse Hospital's Chemical Dependency Treatment Services in New York, the Montana Chemical Dependency Center.
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A functional dependency occurs between two attributes in a database, A and B, if there exists a relationship such that for each value of A there is only one corresponding value of B (A -> B). This can be extended to a functional dependency where A may be a set of tuples (x, y, z) that correspond to a single value B ([x, y, z] -> B). In simple mathematical terms the functional dependency must pass the vertical line test for proper functions. Normalization of a relational database means that the relations (tables) in the database conform to a set of rules for a certain normal form (First - Sixth Normal Form [1-6NF] and/or Boyce-Codd Normal Form [BCNF]). The higher the normal form of a table the less vulnerable it is to data inconsistency and data anomalies formed during updates, inserts, and deletes. Normalization often reduces data redundancy in a database which reduces data inconsistency and anomaly risks. Normalizing a database requires analysis of the closure of the set of functional dependencies to ensure that the set complies with the rules for the given normal form. If the table does not comply with the rules then the table is split following specific procedures to achieve the desired normal form. Every table in a database has a normal form and to make a statement that a database is in a certain normal form (ex. 3NF) means that every table complies with the rules for 3NF.
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Sexual Dependency - film - was created on 2003-05-16.
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Her dependency on the medication served to confirm our belief that she was an addict.
Robert's dependency on his mother was natural at the young age of 5, but now at 35, he's pushing it.
Greenland has been a dependency of Denmark since 1979.
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The Adjudication of dependency is a petition in Pennsylvania under the Rule 1408. This petition requests the Child Dependency to the court like in need of state intervention due to the drug issue.
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Alcoholism is defined as a dependency on alcohol regardless of the consequences.
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Marjorie Bremner has written:
'Dependency and the family' -- subject(s): Choice (Psychology), Dependency (Psychology), Social policy, Welfare state
'Dependency and the family' -- subject(s): Social policy, Welfare state, Choice (Psychology), Dependency (Psychology)
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