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content/notes/13-databases-1.md

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+---
+title: "13-databases-1"
+aliases: 
+tags: 
+- cosc203
+- lecture
+---
+
+# What is a database
+- an integrated collection of data
+- implicit properties
+	- represents some aspect of th real world, called miniworld
+	- is a coherent collection of data with inherent meaning
+	- is designed built and populated with data for a specific purpose
+
+## DBMS
+- a software system designed to store, manage, and facilitate access to the database
+- Oracle, SQL erver, MySQL, MonogDB
+
+## Application program
+- a program that provides access to the dtabase by sending queries and requests for data to the DBMS
+
+![data base system diagram|400](https://i.imgur.com/3xzWCw6.png)
+
+# This course
+- modelling and design of DBs 
+- programming  (SQL + appliation development)
+- DBMS implementation
+
+specifiically *relational databases*
+- ER modelling
+- datbase normalisation
+- SQL
+
+#
+
+
+# Data modelling
+first step in designing database
+- create a data model for a specific problem domain
+
+a model is Defn: a collection of concepts that can be used to describe the structure of a database such as data types, relationsips, and contraints that should hold for the data
+
+schema Defn: a collection of metadata that describes the logical view of a database
+
+noSQL databases are either schema-free or have relaxed schemas
+