2.a - Summary

LINGI2172 - Databases S2a – Summary of S1! UCLouvain - EPL/ICTEAM! 2015-2016

What is a Database again?

What is a Database again?

Expose Information to software layer(s)

Keep everything else hidden!

Key Points for being a DBMS • Database definition! – Focus on information, not (only) storage!!

• Data Independence! – Weak coupling for easier maintenance!

• High-level Specification! – Behavioral guarantees for meeting your requirements (e.g. ACID)!

• Declarative vs. procedural! – Information aims at being queried!

A Database Definition • A Database is a collection of related data! – Where ‘data’ means facts that can be recorded and have an implicit meaning!

• Important notion: The Universe of Discourse! – Also called the Mini-World! – It’s all about what information you need to capture R. Elmasri and S. Navathe, Database Systems, Models, Languages, Design and Application Programming, 6th Edition, Pearson Education, 2011

The Relational Model At a Glance COURSE DEPARTMENT

LINGI2172

DATABASES

…

SOFT.ENG

…

INGI

EPL/INGI

…

LINGI2255

ELEC

EPL/ELEC

…

LELEC2885 IMAGE PROC. OFFERING

INGI

LINGI2172

WEDN. 10h30

BARB01

ELEC

LELEC2885

MONDAY 14h

BARB13

EVALUATION

STUDENT

S1

LINGI2172

A

S1

SMITH

S2

LELC2885

C

S2

JONES

These are “Relations”,! ! we represent them by tables

…

A Relation is all and only about
 giving meaning to (stored) Data OFFERING INGI

LINGI2172

WEDN. 10h30

BARB01

ELEC

LELEC2885

MONDAY 14h

BARB13

INGI’s LINGI2172 course is dispensed on! Wednesday 10h30 at Barb01 The Relational Model per se says nothing about! • How relations are stored! • How data is to be distributed over nodes/servers! • What data types are available! • How tuples (records) are ordered, indexed, etc.

Two Aspects to be Studied

The Interface

The Data Model