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What is the relation between set theory and relational databases?
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∙ 14y ago
DEFINITIONS: Set Theory - branch of mathematics that studies sets, which are collections of objects... Relational Databases - matches data by using common characteristics found within the data set...... YOUR ANSWER: Set theory can be applied to relational databases on effectively organizing data. See more on Relations on Set Theory. Once you understand relations or relationships in mathematics, you will easily be able to organize and simplify your data into your databases.
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∙ 14y ago
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What is the contribution of set theory in rdbms?
set - A collection of well defined and distinct objects. eg:emp={001,002,003,004....}Relation - table(employee)tuple -row(which employee)attribute-column(details about that employee)set theory says what all can be done with relation(table) with various operatorsunion ,intersection,=,!=, etc
What is the difference between classical set theory and fuzzy set theory?
Classical theory is a reference to established theory. Fuzzy set theory is a reference to theories that are not widely accepted.
What is relational algebra in DBMS explain with suitable example?
Relational algebraIn order to implement a DBMS, there must exist a set of rules which state how the database system will behave. For instance, somewhere in the DBMS must be a set of statements which indicate than when someone inserts data into a row of a relation, it has the effect which the user expects. One way to specify this is to use words to write an `essay' as to how the DBMS will operate, but words tend to be imprecise and open to interpretation. Instead, relational databases are more usually defined using Relational Algebra.Relational Algebra is :the formal description of how a relational database operatesan interface to the data stored in the database itselfthe mathematics which underpin SQL operationsOperators in relational algebra are not necessarily the same as SQL operators, even if they have the same name. For example, the SELECT statement exists in SQL, and also exists in relational algebra. These two uses of SELECT are not the same. The DBMS must take whatever SQL statements the user types in and translate them into relational algebra operations before applying them to the database.TerminologyRelation - a set of tuples.Tuple - a collection of attributes which describe some real world entity.Attribute - a real world role played by a named domain.Domain - a set of atomic values.Set - a mathematical definition for a collection of objects which contains no duplicates.Operators - WriteINSERT - provides a list of attribute values for a new tuple in a relation. This operator is the same as SQL.DELETE - provides a condition on the attributes of a relation to determine which tuple(s) to remove from the relation. This operator is the same as SQL.MODIFY - changes the values of one or more attributes in one or more tuples of a relation, as identified by a condition operating on the attributes of the relation. This is equivalent to SQL UPDATE.Operators - RetrievalThere are two groups of operations: Mathematical set theory based relations: UNION, INTERSECTION, DIFFERENCE, and CARTESIAN PRODUCT.Special database operations: SELECT (not the same as SQL SELECT), PROJECT, and JOIN.Relational SELECTSELECT is used to obtain a subset of the tuples of a relation that satisfy a select condition. For example, find all employees born after 1st Jan 1950: SELECTdob '01/JAN/1950'(employee)Relational PROJECTThe PROJECT operation is used to select a subset of the attributes of a relation by specifying the names of the required attributes. For example, to get a list of all employees surnames and employee numbers: PROJECTsurname,empno(employee)SELECT and PROJECTSELECT and PROJECT can be combined together. For example, to get a list of employee numbers for employees in department number 1:Figure : Mapping select and project Set Operations - semanticsConsider two relations R and S. UNION of R and S the union of two relations is a relation that includes all the tuples that are either in R or in S or in both R and S. Duplicate tuples are eliminated.INTERSECTION of R and S the intersection of R and S is a relation that includes all tuples that are both in R and S.DIFFERENCE of R and S the difference of R and S is the relation that contains all the tuples that are in R but that are not in S.SET Operations - requirementsFor set operations to function correctly the relations R and S must be union compatible. Two relations are union compatible if they have the same number of attributesthe domain of each attribute in column order is the same in both R and S.UNION ExampleFigure : UNION INTERSECTION ExampleFigure : Intersection DIFFERENCE ExampleFigure : DIFFERENCE CARTESIAN PRODUCTThe Cartesian Product is also an operator which works on two sets. It is sometimes called the CROSS PRODUCT or CROSS JOIN. It combines the tuples of one relation with all the tuples of the other relation.CARTESIAN PRODUCT exampleFigure : CARTESIAN PRODUCT JOIN OperatorJOIN is used to combine related tuples from two relations: In its simplest form the JOIN operator is just the cross product of the two relations.As the join becomes more complex, tuples are removed within the cross product to make the result of the join more meaningful.JOIN allows you to evaluate a join condition between the attributes of the relations on which the join is undertaken.The notation used is R JOINjoin condition SJOIN ExampleFigure : JOIN Natural JoinInvariably the JOIN involves an equality test, and thus is often described as an equi-join. Such joins result in two attributes in the resulting relation having exactly the same value. A `natural join' will remove the duplicate attribute(s). In most systems a natural join will require that the attributes have the same name to identify the attribute(s) to be used in the join. This may require a renaming mechanism.If you do use natural joins make sure that the relations do not have two attributes with the same name by accident.OUTER JOINsNotice that much of the data is lost when applying a join to two relations. In some cases this lost data might hold useful information. An outer join retains the information that would have been lost from the tables, replacing missing data with nulls. There are three forms of the outer join, depending on which data is to be kept.LEFT OUTER JOIN - keep data from the left-hand tableRIGHT OUTER JOIN - keep data from the right-hand tableFULL OUTER JOIN - keep data from both tablesOUTER JOIN example 1Figure : OUTER JOIN (left/right) OUTER JOIN example 2Figure : OUTER JOIN (full)
What number comes after nine?
Well from what I understand, there is a widely acepted theory the the number 9 goes somewhere in between 8 and 10. But some people question the viablity of this theory, and say that nine could be anywhere between negative infinity and infinity. It you are living in this particular dimension, most people use the between 8 and 10 theory, but this has yet to be proved.
What does Algebraic mean?
Algebra is a branch of mathematics concerning the study of structures, relation and quantity. Together with geometry, analysis, combinatorics and number theory, Algebra is one of the main branches of mathematics.
What has the author David Maier written?
David Maier has written: 'The theory of relational databases' -- subject(s): Database management, Relational databases
What has the author Stefan Stanczyk written?
Stefan Stanczyk has written: 'Theory and practice of relational databases' -- subject(s): Relational databases, Database management
What has the author Stefan K Stanczyk written?
Stefan K. Stanczyk has written: 'Theory and practice of relational databases'
What is the differeence between sceintific management theory and human relation theory?
Scientific management theory focuses on improving efficiency through systematic analysis of work processes and employee tasks, aiming for maximum productivity. Human relation theory emphasizes the importance of social relationships in the workplace, recognizing that employee satisfaction and morale can significantly impact productivity and performance. While scientific management focuses on task optimization, human relation theory emphasizes the importance of human factors in organizational success.
What are the relationships that the relational database is named for?
In database theory, a relation is defined as a set of tuples that have the same attributes. A tuple is also known as a row or record.
What Is Relation Between Professionalism And-theory?
theory does not include practice but professionalism does
Comparison between scientific management theory and human relation theory?
Similarities between the classical and human relations theory
What is the Difference between behavioral science and human relation approach?
Behavioral science focuses on understanding human behavior through empirical research and scientific methods. It emphasizes applying principles from psychology, sociology, and other disciplines to analyze and predict human behavior. On the other hand, the human relations approach focuses on studying how social and psychological factors impact human interactions in organizations, with an emphasis on improving communication, motivation, and group dynamics to enhance productivity and employee satisfaction.
What is the difference between relational and non relational system?
Relational systems store data in tables with predefined schemas and use SQL for querying. Non-relational systems store data in flexible document or key-value formats and use various query languages or APIs for access. Relational systems are well-suited for structured data and complex queries, while non-relational systems are more flexible for unstructured or changing data and offer better scalability.
What is difference between Scientific management theory and human relation theory of Eltom mayo?
i dont know by kenneth mukwena
What is the differences between the human relation theory and the classical theory?
Human relations theory focuses on the value, needs and contribution of the employee; classical theory's emphasis is the good of the organisation and the work.
What is cognitive motivational relational theory?
Cognitive motivational relational theory is a framework that explores how cognitive processes, emotions, and motivation interact in influencing social interactions and relationships. It emphasizes the role of individuals' thoughts and beliefs in shaping their motivation to engage with others and the quality of their relationships. This theory highlights the importance of understanding how cognitive factors contribute to social behavior and relationship outcomes.
