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db1-vt13-RM-ERtoRM

Database Design I - 1DL300; Relational model and translation from ER to RM
by

Sobhan Badiozamany

on 28 January 2013

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Transcript of db1-vt13-RM-ERtoRM

DATABASE DESIGN I - 1DL300 Spring 2013
Sobhan badiozamany
Department of Information Technology, Uppsala University The Relational model (RM) and translation from ER model to RM The relational model Introduced by Dr. Edgar (Ted) F. Codd (1924-2003) in 1970
Codd was a mathematician from Oxford (UK) invented the relational model while at IBM San José Research Lab (USA)
Many (in practice, all) DBMSs are based on the relational data model
Very simple model
A multi billion $ industry
Query using high-level languages
Simple but very expressive.
Operations are based on
the relational algebra (covered in another lecture)
Closedness: Operations in the relational model applies to relations (tables) and produce new relations. Relational model definitions Lets apply the rules! summary Conceptual design/schema Logical design/schema Conceptual model, e.g. expressed in ER
Good to describe a mini-world
On an abstract level, not good for any specific DBMS Implementation model
Describes database design
Data model for a DBMS, here Relational DBMS. R1 R2 R3 O1 O2 R4 An operation can be applied to the result of another operation
several operations can be combined. R6 R5 Informal Table........................................................................................................................................................................................................Relation formal Populated table...............................................................................................................................................................State of a relation Table definition........................................................................................................................................................Schema of a relation Row...........................................................................................................................................................................................................Tuple All possible column values..................................................................................................................................................Domain Column header...............................................................................................................................................................................Attribute A table contains set of rows
Each row represents certain facts that correspond to a real-world entity or relationship.
Each column has a column header that gives an indication of the meaning of the data items in that column. A Relation is a mathematical concept based on the ideas of sets.
A relation contains set of tuples. Integrity constraints..................................................................................................................................................Integrity constraints Domain Keys What is the "Null" Integrity constraints Translating entity types and their attributes Translation of relationships 1-1 Relationship Strong entity types Weak entity types M-N Relationship 1-N Relationship Translation of multivalued attributes and relationships Multivalued attributes Multivalued relationships Elmasri/Navathe ch 3, 8
Padron-McCarthy/Risch ch 5-6 Database systems, Ramez Elmasri and Shamkant B. Navathe Database systems, Ramez Elmasri and Shamkant B. Navathe Database systems, Ramez Elmasri and Shamkant B. Navathe Database systems, Ramez Elmasri and Shamkant B. Navathe ER RM ER to RM mapping But first,
what is the Relational Model? So, this is about translating from ER to tables
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