Computer Science > QUESTIONS & ANSWERS > Arizona State UniversityIFT 200IFT 200- week 4.-ALL ANSWERS CORRECT-GRADED A (All)

Arizona State UniversityIFT 200IFT 200- week 4.-ALL ANSWERS CORRECT-GRADED A

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Review Questions 5.1. Define the following terms as they apply to the relational model of data:  Domain – The range of values of an attribute. It has a logical definition and a data type, or a... format defined for it.  Attribute – A column header is called an attribute. Each attribute is the name of a role played by some domain D in the relation schema.  n-tuple – Each tuple in the relation represents a particular student entity or object. Relation is displayed as a table where each tuple is shown as a row and each attribute corresponds to a column header which indicates a role or interpretation of the values in that column.  relation schema – a relation schema is used to describe a relation; R is called the name of the relation.  relation state – a relation state r(R) is a mathematical relation of degree n on the domains dom(A1), dom(An), which is a subset of the Cartesian product (denoted by x) of the domains.  degree of a relation – The degree (or arity) of a relation is the number of attributes n of its relation schema.  relational database schema – a relational database schema S is a set of relation schemas S ={R1, R2, ……., Rm} and a set of integrity constraints IC.  relational database state – a relational database state 10 DB of S is a set of relation states DB = {r1, r2,……, rm} such that each rj is a state of Rj and such that the rj relation states satisfy the integrity constraints specified in IC. 5.2. Why are tuples in a relation not ordered? A set of tuples is called a relation. Tuples in a relation does not contain a particular order just as elements in a set does not have an order. Relation represent facts at both the abstract and logical [Show More]

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