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To determine keys from functional dependencies, one can use the closure of attributes to identify superkeys and then eliminate any redundant attributes to find the minimal key. This process involves applying the Armstrong's axioms and the closure property to determine the set of attributes that uniquely identify each tuple in a relation.
What else can I help you with?
How entities can be related to each other using primary and foreign keys?
Do you mean ... One-To-Many One-To-One Many-To-Many Many-To-One Vic(S)
Can you make any words on any one row of computer keys?
Yes, on any row but the bottom row.
What is Functional dependency and normalization for database?
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.
How can one determine tight asymptotic bounds for a given algorithm's time complexity?
To determine tight asymptotic bounds for an algorithm's time complexity, one can analyze the algorithm's performance in the best and worst-case scenarios. This involves calculating the upper and lower bounds of the algorithm's running time as the input size approaches infinity. By comparing these bounds, one can determine the tightest possible growth rate of the algorithm's time complexity.
How many blind people use computers in the United States?
Lots do, they just have a special one so what they saygets typed or they hae brail on the keys....
Who specifies the functional dependencies that hold?
Functional dependencies are typically specified by database designers or data architects during the database design process. They define the relationships between different attributes in a relational database, indicating how the value of one attribute is dependent on another. This specification is often based on business rules and requirements that dictate how data elements relate to one another. Ultimately, understanding these dependencies helps in normalization and ensures data integrity within the database.
How can one determine the total number of keys on a piano?
To determine the total number of keys on a piano, count the white and black keys together. A standard piano has 88 keys in total.
Axioms for functional dependencies and inclusion dependencies?
4. Functional dependencyIn relational database theory, a functional dependency is 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 set of attributes Y, also in R, (written X → Y) if, and only if, each X value is associated with precisely one Y value; R is then said to satisfy the functional dependency X → Y. Equivalently, the projection is a function, i.e. Y is a function of X.[1][2] In simple words, if the values for the X attributes are known (say they are x), then the values for the Y attributes corresponding to x can be determined by looking them up in any tuple of Rcontaining x. Customarily X is called the determinant set and Y the dependent set. A functional dependency FD: X → Y is called trivial if Y is a subset of X.The determination of functional dependencies is an important part of designing databases in the relational model, and in database normalization and denormalization. A simple application of functional dependencies is Heath's theorem; it says that a relation R over an attribute set U and satisfying a functional dependency X → Y can be safely split in two relations having the lossless-join decomposition property, namely into where Z = U − XY are the rest of the attributes. (Unions of attribute sets are customarily denoted by mere juxtapositions in database theory.) An important notion in this context is a candidate key, defined as a minimal set of attributes that functionally determine all of the attributes in a relation. The functional dependencies, along with the attribute domains, are selected so as to generate constraints that would exclude as much data inappropriate to the user domain from the system as possible.A notion of logical implication is defined for functional dependencies in the following way: a set of functional dependencies logically implies another set of dependencies , if any relation R satisfying all dependencies from also satisfies all dependencies from ; this is usually written . The notion of logical implication for functional dependencies admits a sound and complete finite axiomatization, known as Armstrong's axioms.Properties and axiomatization of functional dependenciesGiven that X, Y, and Z are sets of attributes in a relation R, one can derive several properties of functional dependencies. Among the most important are the following, usually called Armstrong's axioms:[3]Reflexivity: If Y is a subset of X, then X → YAugmentation: If X → Y, then XZ → YZTransitivity: If X → Y and Y → Z, then X → Z"Reflexivity" can be weakened to just , i.e. it is an actual axiom, where the other two are proper inference rules, more precisely giving rise to the following rules of syntactic consequence:[4].These three rules are a sound and complete axiomatization of functional dependencies. This axiomatization is sometimes described as finite because the number of inference rules is finite,[5] with the caveat that the axiom and rules of inference are all schemata, meaning that the X, Y and Z range over all ground terms (attribute sets).[4]From these rules, we can derive these secondary rules:[3]Union: If X → Y and X → Z, then X → YZDecomposition: If X → YZ, then X → Y and X → ZPseudotransitivity: If X → Y and WY→ Z, then WX → ZThe union and decomposition rules can be combined in a logical equivalence stating that X → YZ, holds iff X → Y and X → Z. This is sometimes called the splitting/combining rule.[6]Another rule that is sometimes handy is:[7]Composition: If X → Y and Z → W, then XZ → YWEquivalent sets of functional dependencies are called covers of each other. Every set of functional dependencies has a canonical cover.
What is functional dependency in computer terms?
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".
How is concept of functional dependency associate with process of normalization?
Functional dependency is a key concept in database normalization, as it defines the relationship between attributes in a relation. It indicates that the value of one attribute (or a group of attributes) uniquely determines the value of another attribute. Normalization utilizes these dependencies to organize data efficiently, eliminating redundancy and minimizing the potential for update anomalies. By identifying and enforcing functional dependencies, databases can be structured in a way that enhances data integrity and reduces duplication.
How do you figure out how a table's relationship is functional?
To determine if a table's relationship is functional, check if each input (or key) in the table corresponds to exactly one output (or value). This can be done by ensuring that no two rows in the table have the same value for the key column. Additionally, examining the table's structure or any associated constraints (like primary keys in a database) can help confirm the functional relationship. If every input consistently leads to a unique output, the relationship is indeed functional.
Why are certain functional dependencies called trivial functional dependencies?
A functional Dependency_theory_(database_theory)(FD) is a constraint between two sets of attributes in a Relational_modelfrom a DatabaseGiven 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.
How are components connected or related to one another?
Components are connected or related to one another through various forms of interaction, such as physical connections, data exchanges, or functional dependencies. In systems, these relationships can be hierarchical, where one component influences or controls another, or they can be collaborative, where components work together to achieve a common goal. The nature of these connections can determine the overall performance and behavior of the system. Understanding these relationships is crucial for system design and analysis.
What is multivalued dependency?
Multivalued dependencies are also referred to as tuple generating dependencies. After the Boyce -Codd normal form the results may be devoid of any functional dependencies but it may encounter multivalued dependencies as the multivalued dependencies also cause redundancy of data. For eg: If there are 3 attributes involved in a relation,A,B, and C.. Then for every value of A we will have respective values for B and C.. But it is a necessary in the 4th normal form that both B and C values are independent of each other. This is represented by .,, A->>B A->>C.. MVD or Multivalued Dependency is a dependency where one attribute value is potentially a "multivalued fact" about another and the attributes must be independent of each other.
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 it called to have one functional kidney?
its called one functional kidney
What are the two crown dependencies of the British Isles?
Pedantically, there is only one crown dependencies in the British Isles. There are actually three Crown Dependencies: the Isle of Man, Jersey and Guernsey. Jersey and Guernsey are collectively called the 'Channel Isles'. They are usually NOT considered part of the British Isles, because they are off the coast of France. That leaves only one Crown Dependency which is part of the British Isles, the Isle of Man.
