1. LIS651 lecture 1 PHP basics, database introduction
Thomas Krichel

2. today PHP part Database theory Introduction to mySQL. we work with
text
numbers
Booleans and flow control
arrays
we reorganize the shop
Database theory
Introduction to mySQL.

3. variable names
Variable name must start with a letter or underscore. They can contain letters, digits and underscores. The following are examples of illegal names
$2drunk
$bottle-content
Variable names are case sensitive. I use lowercase only and add underscores in long names.
It is good to give variables meaningful names.

4. strings a piece of text in PHP is called a string.
A string is often surrounded by single quotes.
print 'I want beer';
$want='beer';
print 'I want $want'; // prints: I want $want
If you want to use the values of variables, use double quotes
print "I want $want";
// prints: I want beer

5. single and double quotes
You can use single quotes to quote double quotes
print 'She wrote: "I want beer." and sighed.';
// prints: She wrote: "I want beer." and sighed.
and vice versa
print "She wrote: 'I want beer.' and sighed";
// prints: She wrote: 'I want beer.' and sighed.
Sometimes it is not obvious when to put single quotes, double quotes, and when to leave them out. If one thing does not work, try something else.

6. the backslash escape
The backslash is used to quote characters that otherwise are special.
print 'Don\'t give me bad beer!';
$kind='bock';
$beer='Festbock';
print "<p class=\"$kind\">$beer</p>";
// prints: <p class="bock">Festbock</p>
The backslash itself is quoted as \\
print "a \\ against beer consumption";
// prints: a \ against beer consumption

7. more backslash escapes
\n makes the newline character
\r make the carriage return (no use in Unix)
\t makes the tab (seldomly used in HTML)
\$ makes the dollar (used in the shop)
$amount='1.50';
print "you owe \$$amount per bottle.";
// prints: you owe $1.50 per bottle.
If the backslash was not there $ would be considered to be a variable.

8. concatenation
This is done with the . operator. It puts two strings together, the second one after the first one.
$cost='5.23';
$message='This costs ' . $cost;
print $message;
// prints: This costs 5.23

9. string functions
There are a long list of string functions in the PHP reference manual. When you work with text, you should look at those string functions at
Working with text is particularly important when checking the input of users into your form.
I am looking at just a few of examples here. You really need to read the reference to see what is available.

10. trim()
trim(string) removes the whitespace at the beginning and the end of the string string. It returns the transformed string.
$input=" Festbock ";
$output=trim($input);
print "|$output|"; // prints: |Festbock|
whitespace is any of the following characters
the blank character
the newline
the carriage return
the tabulation character

11. strlen() strlen(string) returns the length of the string string.
$zip=trim($_POST['zipcode']);
$zip_length=strlen($zip);
print $zip_length;
// hopefully, prints 5

12. strip_tags()
strip_tags(string) removes HTML tags from the string string
$input="<b>But</b>weiser";
print strip_tags($input); // prints: Butweiser
$in="<a href=\" src=\"
print strip_tags($in); // prints nothing, hurray!

13. htmlentities()
htmlentities(string) makes HTML entities out of HTML special chars in the string string. <,>,&, and " are transformed. It returns the transformed string.
$in="What does the <div> element do?";
print htmlentities($in);
// prints: What does the <div> element do?

14. numbers Numbers are set without the use of quotes.
You can +, -, * and / for the the basic calculations.
There also is the modulus operator %. It gives the remainder of the division of the first number by the second
print 10 % 7; // prints 3
Use parenthesis for complicated calculations
$pack=2 * (10 % 7);
print "a $pack pack"; // prints: a 6 pack

15. other number functions
abs() calculates the absolute value
print abs(-3) // prints: 3
print abs(3) // prints: 3
The list of functions that use numbers is

16. geeky increment/decrement
++ is an operator that adds one. The value of the resulting expression depends on the position of the operator
$a=4;
print ++$a; // prints: 5
print $a; // prints: 5
$b=4;
print $b++; // prints 4
print $b; // prints 5
-- works in the same way

17. geeky combined operators
There are some combined operators that change a value and set it to the new one. For example
$a+=$b ;
is the same as
$a=$a+$b;
Same effect for -=, *=, /=, %=, and .=
$a="I want ";
$b="Balitka 8";
$a.=$b;
print $a; // prints: "I want Baltika 8"

18. Boolean value Every expression in PHP has a Boolean value.
It is either 'true' or 'false'.
In certain situation, an expression is evaluated as a Boolean
For example
if(expression)
expression1 or expression2

19. type conversion
In some circumstance, PHP converts numbers to strings and back. It works like magic. It converts numbers to strings when required
$one_in_three=1/3;
print $one_in_three; // prints:
and numbers to
$string="1.500";
$number=3*$string;
print $number;
Sometimes it converts to Boolean!

20. what is truth? All strings are true except All numbers are true except
the empty string
the string "0"
All numbers are true except
0.0
example
$a=5-4-1; // $a is false
Note that variables that you have not assigned contents are false. This includes misspelled variables!!

21. comparison operators
Expressions that are evaluated in Boolean often use comparison operators.
$beer == 'grosswald' // checks for equality
note difference from
$beer='grosswald'; // this is always true
Other comparisons are
< smaller than <= smaller or equal than
> larger than >= larger or equal than

22. logical operators ‘and’ is logical AND. ‘or’ is logical OR.
if($brand=='Budweiser' or $brand="Sam Adams") {
print "Commiserations for buying a lousy beer\n";
} # where is the mistake in this piece of code?
‘!’ is Boolean NOT
These can be combined. Use parenthesis
if((($pints) > 2 and ($vehicle=='car')) or (($pints > 6) and ($vehicle=='bicycle'))) {
print "order a cab!\n"; }

23. variable types Variables in PHP have types. You can check for types
is_numeric()
is_string()
is_int()
is_float()
They all return a Boolean value.
They can be used to check the nature of a variable.

24. if() { }
if(expression) evaluates an expression expression as Boolean, and executes a block of code surrounded by curly brackets if the expression is true.
if($drunk) {
print "Don't drive!\n"; }
Note you don't need to indent the block as done above, but the way Thomas has done it there is pretty much standard, so do it in the same way.

25. if() {} else {}
if you have an if() you can add an else block of code to execute when the condition is false
if($sober) {
print "You can drive\n"; }
else {
print "Check if you are fit to drive\n";

26. elseif() { } You can build chain of conditions if($pints_drunk==0) {
print "You are ok to drive\n"; }
elseif($pints_drunk<3) {
print "Don't use the car, get on your bike\n";
elseif($pints_drunk<=6) {
print "Take a cab home\n";
else { print "Call the local hospital!\n";

27. while() { }
while() { } executes a piece of code while the condition is true
$count=0;
while($count < 100) {
print "Пиво без водки -- деньги на ветер!<br/>";
$count=$count+1; # don't forget to increment $count! }

28. arrays
The variables we have looked at up until now are scalars. They only contain one piece of data.
Arrays are variables that can contain more than one piece of data.
For example, a six pack in conveniently represented as an array of cans of beer.
For another example, a class is a group of people, each having a name, a social security number, etc.

29. numeric arrays
An numeric array has key value pairs where the keys are numbers.
$good_beers[0]="Baltika 8";
$good_beers[1]="Bruch Festbock";
or as follows
$lousy_beers=array("Miller Lite", "Sam Adams", "Budweiser");
print $lousy_beers[0]; // prints: Miller Lite
print $lousy_beers[2]; // prints: Budweiser

30. keeping count in numeric arrays
For numeric arrays, you can add members very simple without keeping track of number.
$beers=array("Karlsberg", "Bruch") ;
$beers[]="Budweiser";
// $beer now has Karlberg, Bruch and Budweiser
print count($beers) ; // prints 3

31. string arrays
Sometimes you need data structured by a string. For example for a price list.
$price['Grosswald Export']=1.45;
$price['Bruch Festbock']=1.74;
// the array $price has strings as keys
An equivalent way to declare this is
$price=array('Grosswald Export' => 1.45, 'Bruch Festbock' => 1.74);

32. array functions
There is a very large number of array functions. They are described in the array function reference.
Now we are just looking at some examples.

33. count() count() returns the size of an array
$price['Grosswald Export']=1.45;
$price['Bruch Festbock']=1.74;
$product_number=count($price);
print "We have $product_number products for you today.";
// prints: We have 2 products for you today.

34. foreach() loop The foreach loop is as follows
foreach($array as $item) {
/* do something */ }
Example
$tray=array('orange','apple','kiwi');
foreach($tray as $fruit) {
print " Thomas has a $fruit,";
} // prints:
// " Thomas has a orange, Thomas has a apple,
// Thomas has a kiwi"

35. another foreach() example
Another example illustrates
print "<table caption=\"price list\">\n";
foreach ($price as $item => $euro_amount) {
print "<tr><td>$item</td>\n";
print "<td>€$euro_amount</td></tr>\n"; }
print "</table>";
This prints the full price list. But it could also do the whole form. This is fabulous!

36. foreach() example from the form
$_GET is an array. You can loop through it.
foreach($_GET as $control => $value) {
print “you set $control to $value<br/>\n”; }

37. the well-aligned price table
$l_r=array('left','right');
$count=0; // counter of elements printed
print "<table caption=\"price list\">\n";
foreach ($price as $item => $euro_amount) {
print "<tr><td align=\"$l_r[$count % 2]\"";
print "$item";
$count++;
print "</td>\n<td align=$l_r[$count % 2]\">
€$euro_amount</td></tr>\n"; }

38. print "</table>\n";
// This produces something like
// <table caption="price list">
// <tr><td align="left">Grosswald Export</td>
// <td align="right">€1.45</td></tr>
// <tr><td align="left">Bruch Festbock</td>
// <td align="right"'>€1.74</td></tr>
// </table>

39. multiple arrays Example $products[0]['name']="Grosswald Pilsener";
$products[0]['price']=1.56;
$products[1]['name']="Grosswald Export";
$products[1]['price']=1.34;
$products[2]['name']="Bruch Landbier";
$products[2]['price']=1.22;

40. printing a debugging representation
$a = array ('a' => 'apple', 'c' => array ('one', 'two'));
print_r ($a); // prints a debugging representation:
Array (
[a] => apple
[c] => Array
[0] => one
[1] => two )

41. restructure the shop
Instead of having two files, one with HTML, the other with PHP, let us have just one. It's easier.
One cool thing to help that is cool is
$_SERVER[PHP_SELF]
It gives the file name of your script in the form. As
you change your script file name, you do not need to change the name of the form submitted.

42. check for submission
We include a hidden element in the form to see if it was submitted
<input type="hidden" name="submitted" value="1"/>
We start the script we check for submission
if($_GET['submitted']) {
// work on the data that was submitted }
else {
// print form

43. define some variables
$form_greet='<h1>Please place your order</h1>';
$form_top="<form action=\"$_SERVER[PHP_SELF]\" method=\"GET\"><table>";
$form_submit='</table><input type="submit" value="I order"/>';
$submit_check='<input type="hidden" name="submitted" value="1"/>';
$form_bottom='</form>';
$order_head="<h1>Results of your order</h1><div>\n";
$order_bottom="Thank you for your order. We will ship when we get your check. Prosit!\n</div>";

44. printing results if($_GET['submitted']) {
$total_euro=0; print $order_head;
foreach($_GET as $number => $amount) {
if($amount > 0 and $products[$number]) {
$pay=$amount*$products[$number][price];
print "$amount bottles of ";
print $products[$number][name];
print " is €$pay<br/>"; $total_euro+=$pay; }

45. print results, start form printing part
$total_dollar=$total_euro*$euro_rate;
$total_dollar=number_format($total_dollar,2);
print "The euro rate is $euro_rate<br/>\n";
print "Your bill is \$$total_dollar\n</div>"; }
else { // print the form
print $form_greet; print $form_top; $product_count=0;
foreach ($products as $prod) {
print "\n<tr><td>";
print $prod['name'];
print "</td><td>";

46. final part, printing the form
print "<input type=\"text\" name=\"";
print $product_count;
print "\" maxlength=\"2\" size=\"2\"/>";
print
print $prod['price'];
print "</td></tr>\n";
$product_count++; // don't forget! }
print $submit_check;
print $form_submit;
print $form_bottom;

47. databases
Databases are collection of data with some organization to them.
The classic example is the relational database.
But not all database need to be relational databases.

48. relational databases
A relational database is a set of tables. There may be relations between the tables.
Each table has a number of record. Each record has a number of fields.
When the database is being set up, we fix
the size of each field
relationships between tables

49. example: Movie database
ID | title | director | date
M1 | Gone with the wind | F. Ford Coppola | 1963
M2 | Room with a view | Coppola, F Ford | 1985
M3 | High Noon | Woody Allan | 1974
M4 | Star Wars | Steve Spielberg | 1993
M5 | Alien | Allen, Woody | 1987
M6 | Blowing in the Wind | Spielberg, Steven | 1962
Single table
No relations between tables, of course

50. problem with this database
All data wrong, but this is just for illustration.
Name covered inconsistently. There is no way to find films by Woody Allan without having to go through all spelling variations.
Mistakes are difficult to correct. We have to wade through all records, a masochist’s pleasure.

51. Better movie database ID | title | director | year
M1 | Gone with the wind | D1 | 1963
M2 | Room with a view | D1 | 1985
M3 | High Noon | D2 | 1974
M4 | Star Wars | D3 | 1993
M5 | Alien | D2 | 1987
M6 | Blowing in the Wind | D3 | 1962
ID | director name | birth year
D1 | Ford Coppola, Francis | 1942
D2 | Allan, Woody | 1957
D3 | Spielberg, Steven | 1942

52. Relational database
We have a one to many relationship between directors and film
Each film has one director
Each director has produced many films
Here it becomes possible for the computer
To know which films have been directed by Woody Allen
To find which films have been directed by a director born in 1942

53. Many-to-many relationships
Each film has one director, but many actors star in it. Relationship between actors and films is a many to many relationship.
Here are a few actors
ID | sex | actor name | birth year
A1 | f | Brigitte Bardot | 1972
A2 | m | George Clooney | 1927
A3 | f | Marilyn Monroe | 1934

54. Actor/Movie table actor id | movie id A1 | M4 A2 | M3 A3 | M2 A1 | M5
… as many lines as required

55. databases in libraries
Relational databases dominate the world of structured data
But not so popular in libraries
Slow on very large databases (such as catalogs)
Library data has nasty ad-hoc relationships, e.g.
Translation of the first edition of a book
CD supplement that comes with the print version
Difficult to deal with in a system where all relations and field have to be set up at the start, can not be changed easily later.

56. databases in web sites
Lots of active web sites are driven by relational databases. All large active web sites are.
The design of a active web site first involves looking at databases.
In a shop situation, we have the following tables
customers
products
orders
orders_products
for multiple to multiple relationship between orders and products.

57. mySQL They are a very successful, open-source vendor of SQL software.
Their product is basically freely available.
We will learn the mySQL dialect of SQL.
We will do this next week.

58. phpmyadmin
phpmyadmin is a set of PHP scripts that create a general purpose interface to work with a mySQL database.
It is written in PHP.
It lives at
You need an account. This is not your wotan account, but a permission to use a database on the mySQL server running at wotan.

59. creating mySQL databases
To create accounts however, I will do it in mySQL directly with you now. After logging into mySQL as the root user, I will issue
CREATE DATABASE user_name;
GRANT ALL ON user_name.* TO user_name IDENTIFIED BY 'secret_word' WITH GRANT OPTION;
user_name is your user name. It is the name of your database as well as the name under which you are logging in.
You will type in the secret word.

60. Thank you for your attention! Please switch off machines b4 leaving!
Thank you for your attention!
Please switch off machines b4 leaving!