Short Intro to PHP and MySQL

SQL, MySQL and PHP Jussi Pohjolainen TAMK University of Applied Sciences

Three-tiered Web Site: LAMP Client User-agent: Firefox Server Apache HTTP Server example request GET / HTTP/1.1 Host: www.tamk.fi User-Agent: Mozilla/5.0 (Mac..) ... response Database MySQL PHP

DATABASES AND SQL

Database Management System ( MySQL ) Database Software for Managing the Database Querys Users

SQL - Database

SQL – is a database computer language used in relational databases

S tructured Q uery L anguage

ANSI and ISO – standard

SQL-86

SQL-89

SQL-92

SQL-1999

SQL-2003

SQL-2006

See features:

http://en.wikipedia.org/wiki/Sql#Standardization

SQL - table

+----+-----------+-----------+-----------------------+--------------+--------+

| id | firstname | lastname | email | mobile | gender |

+----+-----------+-----------+-----------------------+--------------+--------+

| 0 | Pekka | Virtanen | pekka.virtanen@foo.fi | +35840123456 | m |

| 1 | Tiina | Tampio | tiina.tampio@foo.fi | +35848763324 | f |

| 2 | Kaisa | Kekkonen | kaisa.kekkonen@foo.fi | +35840123456 | f |

| 3 | Pasi | Pesukarhu | pasi.pesukarhu@foo.fi | +358412345 | m |

+----+-----------+-----------+-----------------------+--------------+--------+

Example of Creating Table

CREATE TABLE employees (

id INTEGER,

name VARCHAR(20),

salary DECIMAL(8,2),

PRIMARY KEY (id)

);

Datatypes

INTEGER

DECIMAL(L,S)

CHAR(N)

VARCHAR(N)

...

Primary Key

With primary key you differentiate rows from each other

Only one primary key for the table

Remove the Table

DROP TABLE employees;

Adding Information to Table

INSERT INTO employees VALUES (

1,

'Jack North',

3000

);

Deleting Information from Table

-- Delete all rows

DELETE FROM employees;

-- Delete one row

DELETE FROM employees

WHERE id = 1;

Retrieving Information

SELECT *

FROM employees;

--

SELECT name, salary

FROM employees;

--

SELECT name

FROM employees

WHERE id = 1;

SELECT *

FROM employees

WHERE id = 1 AND

palkka < 4000;

Multiple Tables

select * from client;

+----+-----------+-----------+-----------------------+--------------+--------+

+----+-----------+-----------+-----------------------+--------------+--------+

| 4 | Foo | Bar | foo@bar.baz | +35850505050 | f |

+----+-----------+-----------+-----------------------+--------------+--------+

Multiple Tables

select * from product;

+----+-------+-------+

| id | name | price |

+----+-------+-------+

| 1 | Milk | 0.70 |

| 2 | Bread | 2.00 |

| 3 | Egg | 1.50 |

+----+-------+-------+

Multiple Tables

select * from purchase;

+----------+-----------+

| clientID | productID |

+----------+-----------+

| 1 | 1 |

| 2 | 1 |

| 2 | 2 |

+----------+-----------+

3 rows in set (0.00 sec)

Relationship

select * from client;

+----+-----------+-----------+-----------------------+--------------+--------+

+----+-----------+-----------+-----------------------+--------------+--------+

| 4 | Foo | Bar | foo@bar.baz | +35850505050 | f |

+----+-----------+-----------+-----------------------+--------------+--------+

select * from product; +----+-------+-------+ | id | name | price | +----+-------+-------+ | 1 | Milk | 0.70 | | 2 | Bread | 2.00 | | 3 | Egg | 1.50 | +----+-------+-------+ select * from purchase; +----------+-----------+ | clientID | productID | +----------+-----------+ | 1 | 1 | | 2 | 1 | | 2 | 2 | +----------+-----------+ 3 rows in set (0.00 sec)

Query

mysql> SELECT client.firstname, client.lastname, product.name

-> FROM client, purchase, product

-> WHERE client.id = purchase.clientid AND

-> purchase.productid = product.id;

+-----------+----------+-------+

| firstname | lastname | name |

+-----------+----------+-------+

| Tiina | Tampio | Milk |

| Kaisa | Kekkonen | Milk |

| Kaisa | Kekkonen | Bread |

+-----------+----------+-------+

MYSQL

MySQL

Very popular SQL-database

Was developed by Swedish company MySQL AB

In 2008 Sun Microsystems bought MySQL AB

Both GNU GPL and Commercial Licence

Has different UIs: CLI, WEB and GUI

MySQL is used by Google, Wikipedia and Yahoo.

MySQL Usage via CLI (TAMK)

Login to gamma

ssh loginname@tpu.fi

Login to MySQL

mysql –h myX.tpu.fi –u loginname -p databasename

See the databases

show databases;

Change database

use databasename;

Exit

quit

SSH – connection and MySQL

MySQL Tutorial

MySQL Tutorial can be found:

http://dev.mysql.com/doc/refman/5.0/en/tutorial.html

PHP AND MYSQL

PHP and MySQL

PHP has functions that allow access to MySQL Databases

Access is very easy

1. Connect

2. Select Database

3. Query

4. Close connection

1. Connect

$link = mysql_connect('mysql_server',

'mysql_user',

'mysql_password');

2. Select Database

'mysql_user',

'mysql_password');

$db_selected = mysql_select_db('foo',

$link);

3. Query

'mysql_user',

'mysql_password');

$link);

$result = mysql_query("DELETE FROM table;", $link);

4. Close

'mysql_user',

'mysql_password');

$link);

$result = mysql_query("DELETE FROM table;", $link);

mysql_close($link);

mysql_query

INSERT, UPDATE, DELETE, DROP

Returns true or false

SELECT, SHOW, DESCRIBE, EXPLAIN

Returns resource on success, false on error

The returned resource should be passed to mysql_fetch_array()

Retrieving Table

'mysql_user',

'mysql_password');

$link);

$result = mysql_query(" SELECT * FROM table; ", $link);

while ($row = mysql_fetch_array($result))

{

print($row[0]);

print($row[1]);

}

mysql_close($link);

Retrieving Table

'mysql_user',

'mysql_password');

$link);

$result = mysql_query(" SELECT * FROM table; ", $link);

while ($row = mysql_fetch_array($result))

{

print($row["id"]);

print($row["name"]);

}

mysql_close($link);

Retrieving Table

'mysql_user',

'mysql_password');

$link);

$result = mysql_query("SELECT * FROM table;", $link);

while ($row = mysql_fetch_array($result, MYSQL_BOTH ))

{

print($row[0]);

}

mysql_close($link);

Retrieving Table

'mysql_user',

'mysql_password');

$link);

while ($row = mysql_fetch_array($result, MYSQL_NUM ))

{

print($row[0]); // Only number indices

print($row[1]);

}

mysql_close($link);

Retrieving Table

'mysql_user',

'mysql_password');

$link);

while ($row = mysql_fetch_array($result, MYSQL_ASSOC ))

{

print($row["id"]); // Only associative indices

}

mysql_close($link);

Error Handling

Every function in the previous code examples could fail

Connection can fail, sql query can fail etc.

Usually you exit the script when DB fails.

With exit($status) – function, you can stop the execution of the script.

Example of Error Handling 1

'mysql_user',

'mysql_password');

if( ! $link )

{

exit("Error connecting to database");

}

Example of Error Handling 2

'mysql_user',

'mysql_password')

or exit("Error connecting to database");

DESIGNING WEB APPLICATION WITH DB CONNECTION

Maintanence

Implement app with the point of view of maintanence

What if the http server is changed?

What if the database server is changed?

What if you have to change the code in your app?

What if someone else have to change the code in the app?

Configuration files for DB

Create special configuration file for Database configuration.

This file should have constants just for the database connection

You could name it conf/database.php

Example of conf/database.php

<?php

/**

* database.php - holds necessary constants for database connection

*

* Copyright information

*

*

* License

*

* Here should be the license...

*

*/

define("MYSQL_HOST", "myX.tpu.fi");

define("MYSQL_USER", "pohjus");

define("MYSQL_PASSWD", "mypassword");

define("MYSQL_DB", "dbpohjus");

// End of file

?>

Database Instructions

Create instructions for the admin

How to create the database

How to put example data into the database

Hot to delete the database

You could create directory just for this:

doc/sql

install.txt

table-create.sql

table-drop.sql

data-insert.sql

data-delete.sql

select1.sql

table-create.sql

-- table-create.sql This will create neccessary clients-table

--

-- COPYRIGHT

-- Copyright information here

-- LICENCE

-- Licence information here

-- DESCRIPTON

-- Detailed description here

CREATE TABLE clients

(

id INTEGER PRIMARY KEY,

firstname VARCHAR(64) NOT NULL,

...

);

-- End of file

install.txt

FILE IDENTIFICATION

File : install.txt

Time-stamp : <2008-10-17 14:36:53 Jussi Pohjolainen>

Description: Database install, test and remove instructions

TO INSTALL THE DATABASE

Database is installed in following steps:

1. ...

EXAMPLE DATA <for testing or product setup>

An example database can be installed in steps:

1. ...

TO REMOVE THE DATABASE

Making Querys

Create your own class that has Database related methods

These methods can handles also the errors and exceptions

Example of Usage: lib/include.php

<?php

/**

* include.php - file that includes all the necessary files

*

* Copyright information

*

* License

* License here

*/

// Import basic configuration file

require_once("conf/application.php");

// Import database configuration file

require_once("conf/database.php");

// Import Database - class

require_once("class/Database.php");

// Import Table - class

require_once("class/Table.php");

// Import HTMLGenerator- class

require_once("class/HTMLGenerator.php");

// End of file

?>

Example of Usage: index.php

<?php

/**

* index.php – UI for the app

*

* Copyright information + Licence here

*/

// Import all necessary files

require_once("include.php");

function main()

{

print HTMLGenerator::myHeader( TITLE, STYLESHEET );

$result = Database::execute( "select * from clients" );

print Table::toXhtmlTable( $result );

print HTMLGenerator::myFooter();

}

main();

// End of file

?>

Short Intro to PHP and MySQL

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