Relation Model - Relation Model 2 Parts 1 Scheme(Names...

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Sheet1 Page 1 Relation Model 2 Parts - 1. Scheme (Names, Relation type of each field) - 2. Instance (Table - records) Formal Def'n: Denoted as R(f1: D1, f2:D2, . ., fm:Dn) n: natural number, f1/f2: name of column fields, D:type(string,int) Relational Database: Degree of a relation instance: number of fields(columns) Cardinality: number of tuples(rows) A Relational database: collection of relations with distinct relation names. A relational database scehem: collection of schemas for the relations in the database A instance of relational database: a collection of relational instances, on per relational scheme in the database scheme/. Relational Query Language -A major strength of the relational model: supports simple, powerful querying of data. - Queries can be written intuitively, and the DBMS is responsible for efficient evaluation. - DDL - Data definition Language - A subset of SQL that supports the creation, deletion and modification of tables. Integrity Constraints (ICs)
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This note was uploaded on 02/14/2010 for the course COMPUTER S COIS-3030 taught by Professor Hircock during the Spring '10 term at Trent University.

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Relation Model - Relation Model 2 Parts 1 Scheme(Names...

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