DATABASES An introduction
EDGAR FRANK (E.F.) CODD The Father of Relational Database Systems
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E.F. CODD ACHIEVEMENTS His idea was to represent data in a set of tables.
WHY USE A DATABASE?
Save it for later ~ has value ~ for analysis later on
..there are many reasons
Online, native and mobile users have to save their data
A database is a collection of ¡®things¡¯, organized so that it can easily be accessed, managed, and updated.
WHY NOT USE FILES?
Not very efficient.
Doesn¡¯t handle transactions
Scale to millions of users?- not really.
STANDARD CONCEPTS
Table Column
Primary Key
Foreign Key
A set of rows in your model One aspect of your model
A set of columns Uniquely identifies a row
A primary key from another table
DDL VS DML
Data Manipulation Language
Data Definition Language
CHAR VARCHAR
TIMESTAMP/DATE NUMBER
BLOB CLOB/TEXT
Fixed-length strings Variable-length strings
A date (formatted) A number
For binary object For large text
DATA TYPES
FIRST EXAMPLE
CONSTRAINTS
FOREIGN-KEYS
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