Database basics

CGS 2835 Interdisciplinary Web Development
Web
Database
Useful
Web Apps
+

The Value of Databases
• Databases and Database Management Systems (DBMS)
transform large quantities of data into specific and
valuable information for accomplishing some goal.

AMP
•Apache – open source Web server
•MySQL – open source database
•PHP – programming language that
works in HTML to provide
interactivity with MySQL

Database
Server
Web
ServerHTML REQUEST w/DATAHTML REQUEST w/DATA
SQL CommandSQL Command
PHP

Database
Server
Web
Server
PHP
data
PHP-created HTML

MySQL
Database
Server
PHPdata
PHP-created HTML
SQLSQL
Our Focus

Databases

File or Table
Database
• A collection of data organized to meet user’s
needs.
Records
(Entities)
Field
(Attribute)

Database Fields
• Fields are set to hold
specific types of data.

Database
A Database
is a
collection of
files/tables

Database Heirarchy
Table

Keys and Primary Key
• Key: A field in a record that is used to identify
the record
• Primary key: A field that uniquely identifies a
record
– A primary key field prevents duplicate records
from occurring in a table.

Primary Keys
• User identification number
• Sometimes email addresses are used as a unique
login, assuming two people cannot have the same
email
• A number is faster to look up, so a unique number
is often still generated

Primary Key

The Relational Model
• In a relational database, tables are linked (related) through
common fields.
• This can remove redundant data, and organize information

“Flat” database
userID First Name Last Name Email, …, … Message
1 Geo Miller …, … , … Hello!
2 Ken Baldauf …, … , … Greetings, how
are you?
1 Geo Miller …, … , … Doing well
2 Ken Baldauf ……, … , … Great!

“Relational”
databaseuserID First
Name
Last
Name
Email, …,
…
1 Geo Miller …, … , …
2 Ken Baldauf …, … , …
userID Message
1 Hello!
2 Greetings, how
are you?
1 Doing well
2 Great!

Relation Types
• One-to-many
– Makes use of primary key
– Example: one person makes
many posts
• One-to-one
– A piece of data only relating to one
record
• Many-to-many
– An item can have many sellers
and sellers can sell that item
many times

MySQL
An open-source, relational database

MySQL - Installing
• Some servers require an administrator to install
• On your own machine, there are installation packages for
AMP
• On Codio:
– parts install mysql
– parts start mysql
• On many linux distributions:
– apt-get install mysql-server
– service mysql start

MySQL – Creating a Database
Creating a database in MySQL is traditionally done with a terminal that has
administrator access to the MySQL server.
CREATE DATABASE IF NOT EXISTS “databasename”
A MySQL user must be created and given access to use the new database
CREATE USER IF NOT EXISTS “username”
SET PASSWORD FOR “username”=PASSWORD(“password”)
GRANT ALL PRIVILEGES ON “databasename” TO “username”
IDENTIFIED BY “password”

phpMyAdmin
is a popular application
for managing mySQL
databases.
Here you can click a
database name to access
its properties and tools.
Note that whenever
prompted for charset or
collation select UTF-8
Unicode (utf8).

Access MySQL Database
We will use phpMyAdmin
to:
•Create tables in databases
•Create fields in the tables
•Manage the database
•Examine table data
We will use PHP to:
• Enter records into tables
from HTML forms
• Read records from tables
and output to HTML pages

When I click my database link in phpMyAdmin, I am prompted to create a table.

Then I create fields for my table.

I can then use the
Insert tab to enter
records into the table.

The browse buttons allows you to view the contents of the table.

You can also run SQL
queries on your data from
within phpMyAdmin.

MySQL & phpMyAdmin
• phpMyAdmin is a useful tool for manipulating mySQL
databases; however, in order to work with Web-generated
data, the mySQL database must be accessed from the HTML
code using PHP.
MySQL
Database
Server
SQLSQLSQLSQL
PHP

MySQL & phpMyAdmin
• Either method of interacting with the database
requires knowledge of SQL
MySQL
Database
Server
SQLSQLSQLSQL
PHP

Database basics

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