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I4DAB1 Autumn 2007

I4DAB1 Autumn 2007. Introduction Some simple rules. Sow what …. Databases (DB) is an old technology when looking at IT’s. As with all other information technologies, using DB together with another technologies gives some “constraints”

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I4DAB1 Autumn 2007

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  1. I4DAB1 Autumn 2007 Introduction Some simple rules.

  2. Sow what… • Databases (DB) is an old technology when looking at IT’s. • As with all other information technologies, using DB together with another technologies gives some “constraints” • DAB1 looks at how to design and implements a Relational Database • And to use a database together with some OO-code

  3. Constraints ..Wich? • Using an already implemented database is relative simple • Designing it may be cumbersome • You already know that from doing your OO modeling. • How do you implement an association? • How do you setting up a model?

  4. “Rule 1” • Associations in Object Orientation: • Inheritance (Generalization/Specialization) • Composition • Aggregation • Others..? No • becomes all to Relationships in DB orientation! When using a Relational DB

  5. “Rule 2” • What about classes and objects? • An OO class becomes one or more relations • An OO object becomes one or more Tuples /records in one or more relations. • OO attributes becomes DB attributes. • And the methods do not exist! (well.. At least for a little time)

  6. “Rule 3” • One more rule is needed.. • Relations (Classes?) are implemented in tables • Tuples/Records are rows in the table • Attributes are columns in the table

  7. “Rule 4” • One more rule too, is “needed” • What we consider references in OO and relationships in RDB are implemented as Keys in the Relational Database Managaement system. Primary or Foreign Key

  8. “Rule 5” • And yet another rule • “Talking” to a Relational Database Management System (RDBMS) is done in Structured Query Language (SQL) Data Definition Language (DDL) Data Manipulation Language (DML) • RDBMS “talks” to any systems that talks SQL DDL and DML.

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