Website Development

Working with Databases

What you will achieve today!

•Connecting to mySql•Creating tables in mySql•Saving data on a server using mySql•Getting data from the server using mySql

: Customer browser

request service

access page

interpretset data

present html

return html

get data

get data

databasescripting language

web server

Reminder of the general process

today’semphasis

The database

A relational database is made up of tables (sometimes known as relations)

Tables are made up of rows (records) and columns (fields, attributes)

Table structure is described in terms of its columns (fields, attributes) E.g. cars (make, model, doors, fuel, cost)

Tables are usually linked to other tables via relationships

Outline

MySQL PHPMyAdmin Simple database communication using PHP

MySQL is a relational database management system. A relational database stores data in separate tables rather than putting all the data in one big storeroom. This adds speed and flexibility. The tables are linked by defined relations making it possible to combine data from several tables on request. The SQL part of MySQL stands for "Structured Query Language" - the most common standardized language used to access databases.

http://www.mysql.com/information/index.html

MySQL

Lightweight Easy to administer Runs on low power machines Great for development Not quite there when compared to Oracle,

MS SQL Server or IBM DB2 but coming along fast (http://www.devx.com/dbzone/Article/20743 )

Installing on your machine

If you are going to work at home with PHP/MySQL I recommend one of the distributed packages for web development

The one we use at uni is called Wamp and is available from http://www.en.wampserver.com/

There are other alternatives

GUI

Most common is phpMyAdmin Hermes link is

http://hermes.hud.ac.uk/phpMyAdmin/ Normal username and password

Let’s have a look at it…

The Four SQL Commands

SELECT INSERT UPDATE DELETE

These only affect values in the database, not the structure, but once you know these four you are set for life*

* not guaranteed

SELECT The example table is called "Cars" Each record is made up of data describing

ID Make Model Doors Fuel and Cost

The SQL to retrieve all rows and all columns is:-   SELECT * FROM Cars

The * indicates that all columns from ‘Cars’ are to be included. This could have been written as:-   SELECT ID Make Model Doors Fuel and Cost FROM Cars

Query result

The code for all (*) would result in the following being returned

SELECT *FROM Cars

1 Audi A4 4 Petrol £19,3002 Audi A3 2 Petrol £16,2503 Audi A4 Avant 5 Petrol £20,4004 Audi A6 4 Diesel £28,880..etc

More precise

SELECT Model FROM Cars

A4A3A4 AvantA6..etc

More precise

SELECT Model,Fuel

FROM Cars

A4 PetrolA3 PetrolA4 Avant PetrolA6 Diesel..etc

Conditional SQL ?

We can use WHERE, along with = <> < > >= <= BETWEEN and LIKE, to narrow down our search:

SELECT Model FROM Cars WHERE Fuel='Diesel'

A6CorollaCorolla330 ..etc

Conditional query

SELECT Model,Fuel FROM Cars WHERE cost<10,000

Corolla PetrolCorolla PetrolCorolla PetrolCorolla DieselCorolla Petrol..etc

Wild cards and Like

SELECT Model FROM Cars WHERE Model LIKE '3%'

323323 Coupe330

Conditional logic

SELECT Model,Fuel FROM Cars WHERE cost BETWEEN £20,000 AND £25,000

A4 Avant Petrol

Multiple conditions

With AND and OR we are not limited to one condition:

SELECT Model,Fuel,Cost FROM Cars WHERE cost<20,000 AND Model = 'Audi'

A3 Petrol £16,250

The IN Keyword This is a neat way of doing multiple ORs. For example, suppose

we wanted a listing of all rows where the make is “AUDI” or “ALPHA”

We could obviously do this with an OR but we can also do it with IN.

   SELECT * FROM Cars WHERE MAKE IN (“AUDI”, “ALPHA”)  You can have as many alternatives as you like in the brackets

above.

The BETWEEN Keyword

We want to list all rows where cost is greater than or equal to 10000 and less than or equal to 20000. We could do this as

  SELECT * FROM Cars

WHERE cost >= 10000AND cost <= 20000

  An alternative way of writing this is to use the BETWEEN keyword.  SELECT * FROM Cars

WHERE cost BETWEEN 10000 AND 20000

INSERT

INSERT INTO table_name VALUES (value1, value2,....)

Or INSERT INTO table_name (column1,

column2,...) VALUES (value1, value2,....)

UPDATE

UPDATE table_name SET column_name = new_value WHERE column_name = some_value

Multiple values with a comma seperated UPDATE table_name SET column_name =

new_value, column_name2 = new_value2 WHERE column_name = some_value

DELETE

DELETE FROM table_name WHERE column_name = some_value

Tutorial

Go to http://www.w3schools.com/sql/sql_tryit.asp and ‘play’ with SELECT sql Try the examples on the page and create a few of

your own

Use phpMyAdmin at http://hermes.hud.ac.uk/phpMyAdmin to ‘play’ with a mysql database

Accessing MySQL from PHP

Connecting to PHP

We can now write SQL and setup our MySQL database

But we want to be able to talk to the database using PHP

Its easy!

For now simple table editing (update data, delete etc), later database editing (create, dump tables etc)

Creating the connection

mysql_connect($hostname, $user, $password);

Then choose a database…

mysql_select_db(‘carsDB’);

Now ask it a question…

$result = mysql_query(“SELECT * FROM Cars”);

Lets see how many results came back…

$num = mysql_num_rows($result);

Now output it to the screen…

Options for dealing with $result mysql_fetch_row - returns row as enumerated

array mysql_fetch_array – returns row as an

associative array

mysql_fetch_row used to be fastest, but mysql_fetch_array is the preferred favourite now

Output to the screen…

while($row = mysql_fetch_array($result))

{

print($row[‘Make’] . $row[‘Model’] . $row[‘Price’] . “<br/>”);

}

Putting data into the database

Example uses cars database

Make Model Price

Smart Roadster 14000

Rover 216si 1800

Robin Reliant 10

Psuedo code

Take inputs from form Write sql string including inputted data Connect to database Run sql command string Check to see if it was successful

The form

Example html

<form method="post" action="cars_process.php">

Make:<input name="Make" type="text" /><br/>

Model:<input name="Model" type="text" /><br/>

Price:<input name="Price" type="text" /><br/>

<input name="submit" type="submit" value="Add to Database" />

</form>

Get data from the form

$Make = $_POST['Make'];

$Model = $_POST['Model'];

$Price = $_POST['Price'];

Create the sql string

$sql = "INSERT INTO cars (Make,Model,Price) VALUES ('$Make','$Model',$Price)";

Connect to mysql and the database

mysql_connect('localhost','root')

or die("cant talk to mysql");

mysql_select_db(‘cars')

or die("cant connect to the database");

Run the mysql command

$result = mysql_query($sql);

Check to make sure it was successful

if(mysql_affected_rows() == 1)

{

print("yay, it worked");

}

else

{

print("something went horribly wrong!");

}

Why 2 files?

Sometimes we need everything to be done in one file

E.g. I fill in a form, submit to another page, but something went wrong, now I have to go back and fill in everything again!

To solve this do all the processing in one page where the form submits to itself.

<?php$Make = $_POST['Make'];$Model = $_POST['Model'];$Price = $_POST['Price'];$submit = $_POST['submit'];$success = 0;if ($submit == "Save" && $Make != NULL && $Model != NULL && $Price != NULL){

$sql = "INSERT INTO cars (Make,Model,Price) VALUES ('" . $Make . "','" . $Model . "'," . $Price . ")";mysql_connect('localhost','root')

or die("cant talk to mysql");mysql_select_db(‘cars')

or die("cant connect to the database");$result = mysql_query($sql);if(mysql_affected_rows() == 1) {

print("yay, it worked");$success = 1;

}else { print("something went horribly wrong!"); }

}if($success != 1) {?><form method="post" action="<?php print($_SERVER['PHP_SELF']); ?>">Make:<input name="Make" id="Make" type="text" value="<?php print($Make); ?>" /><br/>Model:<input name="Model" id="Model" type="text" value="<?php print($Model); ?>" /><br/>Price:<input name="Price" id="Price" type="text" value="<?php print($Price); ?>" /><br/><input name="submit" type="submit" value="Save" /></form><?php}?>

Editing data in the database

Pseudo code Find the data to be changed from the database Output the data into an editable area (e.g. a form) Resubmit the data Update the database

Connect to the databasemysql_connect('localhost','root')

or die("cant talk to mysql");mysql_select_db(‘cars')

or die("cant connect to the database");

$sql = "SELECT * FROM cars";

$result = mysql_query($sql);

while($row = mysql_fetch_array($result)){

print("$row[0] $row[1] - <a href=\"editcar.php?Make=$row[0]&Model=$row[1]&Price=$row[2]\">edit</a><br/>");}

$Make = $_GET['Make'];$Model = $_GET['Model'];$Price = $_GET['Price'];$success = 0;$submit = $_GET['submit'];if($submit == "Update" && $Make != NULL && $Model != NULL && $Price != NULL){

$sql = "UPDATE cars SET Make='$Make' , Model='$Model' , Price=$Price WHERE Make='$Make' AND Model='$Model'";mysql_connect('localhost','root')

or die("cant talk to mysql");mysql_select_db(‘cars')

or die("cant connect to the database");$result = mysql_query($sql);if(mysql_affected_rows() == 1){

print("yay, it worked");$success = 1;

}else { print("something went horribly wrong!"); }

}if($success != 1) {?><form method="get" action="<?php print($_SERVER['PHP_SELF']); ?>">Make:<input name="Make" id="Make" type="text" value="<?php print($Make); ?>" /><br/>Model:<input name="Model" id="Model" type="text" value="<?php print($Model); ?>" /><br/>Price:<input name="Price" id="Price" type="text" value="<?php print($Price); ?>" /><br/><input name="submit" type="submit" value="Update" /></form><?php}

A whole system…

Admin area would need A menu A page for viewing data A page for adding new data A page for editing existing data A page for deleting existing data

Tutorial Exercise

From last week… Make a simple database in phpMyAdmin

Add a table, e.g. cars and populate with dataAdvanced users can write php to create the tables

Write a simple php file to access database and output results to the screen

‘tart up’ your output page to look more readable Plus new…

Create new files for editing and adding data Create a little menu (i.e. a mini admin site)

If you can do all that

You can do the PHP part of the coursework

Tutorial

Make a simple database in phpMyAdmin Add a table, e.g. Guestbook and populate with

data Write a simple php file to access the

database and output results to the screen Tidy up your output page to look more

readable