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PHP

PHP is one of the most widespread and effective programming languages for the WEB and it is also

very simple to understand. Moreover, we can find many free software to make the code we write run.

  The file to program in php must always have php extension, and it also supports all HTML tags. This text is aimed at beginners, long and complex examples are not used in order to learn faster without detracting from the effectiveness of what you learn and also makes sure that even the explanations are not long and boring doing so the reader is put in a position to learn directly by programming, since I think that programming as everything is learned by practicing it.

  All the examples in this text have been done to create safe and error-free examples.

  INDEX

  1 Variables

  2 Arithmetic operators

  3 Comparison operators

  4 Instruction if

  5 Instruction if else

  6 Array

  7 The increment operator

  8 The decrease operator

  9 The for cycle

  10 The while loop

  11 Instruction break

  12 Instruction continue

  13 Take the values from a form

  14 Instruction switch

  15 Logical operators

  16 Instruction exit

  17 The rand function

  18 Pick up the date from the server

  20 The function strlen

  21 The foreach cycle

  22 Instruction empty

  23 Functions

  24 Static Variables

  25 The constants

  26 Create a folder

  27 Delete a folder

  28 Take the IP address

  29 Write and read files

  30 Check to see if a file exists

  31 Delete a file

  32 Upload file

  33 Session variables

  34 Cookie

  

35 Turn characters into lowercase

  

36 Turn characters into uppercase

  37 Format a number

  38 Look for a value in an array

  39 Instruction die

  

41 Look for a value in a tables of a DB

  42 Insert a record

  43 Change a record

  44 Delete a record

  1) Variables

  

Like all programming languages we find the variables, which are entities in which we will store our

data as numbers, alphanumeric characters, etc.

  In PHP to declare a variable, just precede it with the $ symbol. Example:

  <?php $Nome = “Mario”; echo ($Nome); ?>

  

We have assigned to the variable Name the string Mario, if we make this piece of code we see that

the string will be printed.

  The strings must be enclosed in double quotes as in the example. Example 2:

  <?php $Numero = 20;

  ?>

  

With the second example, we declared a variable and assigned it the value of 20, then with the echo

function we had it printed on screen.

  As for the assignment of a value to a variable, we can also declare a variable and then assign it a value later.

  Example:

  <?php $Nome; $Nome=Mario ?>

  2) Arithmetic operators

  

The arithmetic operators as we all know are addition, subtraction, multiplication and division and

module. Let's see what the symbols are and how they are used in PHP.

  Sum of two numbers:

  <?php

  $Numero1=20; $Numero2=10; echo($Numero1 + $Numero2);

  ?> Division of two numbers:

  <?php $Numero1=20; $Numero2=10; echo($Numero1 / $Numero2); ?>

  Subtraction of two numbers:

  <?php $Numero1=20; $Numero2=10; echo($Numero1 - $Numero2); ?>

  

Multiplication of two numbers:

  <?php $Numero1=20; $Numero2=10; echo($Numero1 * $Numero2); ?>

  

Module between two numbers:

  <?php $Numero1=20; $Numero2=10; echo($Numero1 % $Numero2); ?>

In this case 0 will be returned.

  3)

  

Comparison operators

The comparison operators are used to compare two values and to see if they are equal or different in

this case see also which is the major or the minor.

  Their symbols are: Minor < Minor or equal <= Equal == Greater > Greater or equal >= Different != To check if two values are the same, the operator is double the same, to be careful because at the beginning one is often confused.

  So how can we easily guess if we have two numbers such as 5 and 12 if we write:

5 <12 will be returned true, it will be true even if we write 5 <= 12 because the comparison says that

5 must be less than or even equal to 12 in this minor case and therefore returns true. The same thing for the greater and greater equal then: 12> 5 true; 12> = 5 true.

  As for the comparison the same if we write 5 == 5 will be true.

  If we write 12! = 5, it will return true.

  I can also compare two strings for example: $stringa1 = ”Ciao”; $stringa2 = “Buongiorno” If I write that: $stringa2 == $stringa2 it will be false instead $stringa1 != $stringa2 it will be true.

  4) Instruction if

  

With the if statement we can have instructions executed or not based on whether the condition is true

or false.

  Example:

  <?php $numero1=20; $numero2=10; if($numero1 == $numero2)

   { echo ("Istruzione eseguita"); } ?> Echo education will never be performed.

  If instead: 5)

  

Instruction if else

With the addition of else we can make sure that if the expression is true, the statement that is

immediately after the if is executed, if it is false, the statement contained in the brackets of the else is

executed. Example:

  <?php $numero1=20; $numero2=10;

   if($numero1 >= $numero2) { echo ("Prima stringa"); } else { echo("Seconda stringa"); } ?>

  

In this case it will appear "Prima stringa"

  <?php $numero1=20; $numero2=10; if($numero1 == $numero2) { echo ("Prima stringa");

   else { echo("Seconda stringa"); } ?>

  In this case it will appear "Seconda stringa" 6)

  Array Arrays are a collection of all of the same type, such as we can declare an array that contains 20 variables, but they are all of the same type.

  To access an element of an array we use an index that indicates the position of the element. For

example, if we consider an array of 10 elements, the first element has index 0 while the last element

has index 9. Let's see how to declare uin array and how to use it. Example:

  <?php

  $nomi=[10]; $nomi[0]="Gianni"; $nomi[1]="Giuseppe"; $nomi[3]="Mario"; echo ($nomi[0]." ".$nomi[1]); ?>

  

If we make the code written above the echo function will display the string Gianni and Giuseppe, in

fact they are the first and the second element.

  We can also use an array by directly assigning the values as in the following example:

  <?php $Lista=array("Gianni", "Giuseppe", "Mario", "Michele"); echo ($Lista[0]." ".$Lista[1]." ".$Lista[2]." ".$Lista[3]); ?> If we execute the code, the four names inserted between the brackets will be written.

  7)

The increment operator

  

The increment operator is used to increment number 1 every time a code is executed, this operator is

++ and we see how it is used.

  If we write:

  <?php $Numero=3; $Numero++; echo("La variabile é stata incrementata di 1 infatti adesso il suo valore è: "); echo $Numero; ?> Then placing the ++ operator after the variable as in the example.

  8)

  

The decrease operator

The decrement operator serves to decrease the value of a variable by 1 each time a code is executed,

this operator is - - and is used identically to the increment operator.

  Example:

  <?php $Numero=3; $Numero- -; echo("La variabile é stata diminuita di 1 infatti adesso il suo valore è: "); echo $Numero; ?>

  9)

The for cycle

The for loop as well as other types of cycles serve to perform an operation several times.

  They are useful when, for example, we go to read a file, then we can use a loop that starts at the beginning of the file and reads everything until the end of the file, scroll through the records of a database or scroll through the indexes of an array and more.

  <?php for ($i=0; $i<=10; $i++) { echo($i."<br>"); } ?>

  As we see the for loop between its parentheses we put a starting point that is 0, then the cycle

continues until the variable does not exceed the value 10, in fact it continues until the condition in the

second place of the brackets is true, and finally an increase to the variable that in this case is 1. By executing this cycle, the numbers 0 to 10 will be displayed. We can also give a different increase as in the following example:

  <?php for ($i=0; $i<=10; $i=$i+2) { echo($i."<br>"); }

  Let's take a last example we apply a for loop to the array we have seen in the previous topic to display all the names:

  <?php $Lista=array("Gianni", "Giuseppe", "Mario", "Michele"); for ($i=0; $i<4; $i++) { echo($Lista[$i]."<br>"); } ?>

  10)

The while loop

  The while loop as the for loop repeats one or more statements until the condition in parentheses becomes false.

  

In the while loop the increment of the variable we will go to insert it in the inside of the same loop as

we see in the following example:

  <?php $i=0; while($i<4) { echo($Lista[$i]."<br>"); $i++; } ?> We get the display of the names contained in the array.

  

Or let's take another example of a cycle that counts from 0 to 10:

  <?php $i=0; while($i<=10) { echo($i."<br>"); $i++; } ?>

  11) Instruction break

  

With the keyword break we can get out of a cycle before it ends, so that what happens is what we

have to do is put a condition that will get us out of the loop when we want, let's see an example

  <?php for($i=0; $i<=20; $i++) { echo($i); echo("<br>"); if($i==11) { break; } }

  ?>

  

If we execute the code above when the variable has the value 11, the break is executed, if instead we

try to insert the break instruction without delay, the cycle will never be executed.

  The same applies to the while loop, try to run the following code.

  <?php $i=0; while ($i<20) { echo($i); echo("<br>"); if($i==11) { break; } $i++; } ?>

  12)

   Instruction continue

For example, if we are in a for loop and we want an instruction not to be executed if a certain

condition occurs, we can write a code as follows:

  <?php for ($i=0; $i<=10; $i++) { if($i==5) { continue; } echo($i); echo("<br>"); } ?> If we do the example above we see that the number 5 is not written.

  13)

Take the values from a form

  

Now we will see how to get values from text boxes and some other input method and then pass them

to variables and then be able to process them.

  We begin to create an HTML form and insert two text boxes

  <html> <body> <form action="input.php" method="post"> Inserisci qualcosa nelle caselle: <br><br> Casella 1: <input type="text" name="testo1"/> <br><br> Casella 2: <input type="text" name="testo2"/> <br><br> Seleziona qualcosa dalla casella: <select name="combo1"> <option value="val1">valore_1</option>

   <option value="val2">Valore_2</option> <option value="val3">Valore_3</option> <option value="Val4">Valore_4</option> </select> <br><br> <input type="submit" value="OK"/> </form> <?php $variabile_1=$_POST["testo1"]; $variabile_2=$_POST["testo2"]; $variabile_3=$_POST["combo1"]; echo ("Il primo numero inserito è: ".$variabile_1); echo ("<br>"); echo ("Il secondo numero inserito è: ".$variabile_2); echo ("<br>"); echo ("Il valore selezionato è: ".$variabile_3); ?>

   </html>

  

As we see in the example we have inserted two text boxes called testo1 and testo2, which then in the

code by their name we have inserted in the variables named variable_1 and variable_2 and in the same way to get the data from the combobox.

  14)

Instruction switch

  With the switch we can run a series of comparisons and then run a command based on the result of comparisons. We see practically so we realize its operation.

  <html> <body> <form action="input.php" method="post"> Seleziona qualcosa dalla casella: <select name="combo1">

   <option value="1">1</option> <option value="2">2</option> <option value="3">3</option> </select> <br><br> <input type="submit" value="OK"/> </form> <?php $variabile_1=$_POST["combo1"]; switch ($variabile_1) { case "1": echo ("Hai scelto il primo valore"); break; case "2": echo ("Hai scelto il secondo valore");

  break; case "3": echo("Hai scelto il terzo valore"); break; default: echo ("Nessun valore scelto"); } ?> </body> </html>

  As we see from the combobox we select an option and then it is passed to the variable, then the

inserted value is checked in the switch and the corresponding command is executed based on the

entered value, if the variable is empty or no comparison is true the default command is executed .

Let's take another example where the background color of the page is changed.

  <html> <body>

  Seleziona il colore dalla casella: <select name="combo1"> <option value="1">Rosso</option> <option value="2">Verde</option> <option value="3">Blu</option> </select> <br><br> <input type="submit" value="OK"/> </form> <?php $variabile_1=$_POST["combo1"]; switch ($variabile_1) { case "1": echo ("<body bgcolor='#ff0000'>");

  case "2": echo ("<body bgcolor='#00ff00'>"); break; case "3": echo("<body bgcolor='#0000ff'>"); break; default: echo ("Nessun valore scelto"); } ?> </body> </html>

  15) Logical operators

  

With logical operators we can perform two or more comparing two or more expressions, they are the

AND, the OR, and the NOT.

  Their sibles are && for the AND, || for the OR and ! for the NOT.

  AND operator Let's see how they work, then the AND operator when verifying two or more conditions returns true only if all conditions are true

  <?php If (3<5 && 4>1 && 10<20) { echo ("I confronti sono tutti veri"); } else { echo ("I confronti sono falsi o almeno uno risulta falso"); } ?> If we make the list written above, the string will be written. Comparisons are both true.

  

If we try to change something, for example in the last comparison, we write that 10> 20 will come out of the string I confronti sono falsi o almeno uno risulta falso OR operator The OR operator returns true if at least one of the comparisons is true.

  Then we see the following code:

  <?php If (3<5 || 4<1 || 10>20) { echo ("Vi è almeno un confronto che risulta vero"); } else { echo ("I confronti risultano tutti falsi"); } ?>

  In the example we said that 4 is less than 1 and 10 is greater than 20, but the total result is true

because we have remained that 3 is less than 5, if we try to change even the first putting 3 greater than

5 then they are all false then the string will appear and the comparisons are all false.

  NOT operator

The NOT operator inverts a result making it change from true to false and vceversa, in fact we try to

run the code that follows then rewrite it with the operator NOT and see how it changes.

  <?php If (5==5) { echo ("I due numeri sono uguali"); } else { echo ("I due numeri sono diversi"); } ?>

  So far everything flows as written ie the string is printed I due numeri sono uguali

Now let's try to insert the NOT operator as follows, let's run the code and see that the result will say

I due numeri sono diversi

  <?php

  If (!(5==5)) { echo ("I due numeri sono uguali"); } else { echo ("I due numeri sono diversi"); } ?>

  16)

Instruction exit

  

With the exit keyword we can end the flow of a code, so if our program is running when it encounters

the keyword exit exits.

  

We have two examples that contain a cycle that counts from 0 to 20, the first we do not insert the exit

then print all the numbers on the page, while in the second code we insert the exit before the cycle and

we can see that the cycle will not be executed because the flow ends.

  <?php for ($i=0; $i<=10; $i++) { echo ($i.", "); } ?> The code written above will be executed.

  <?php exit; for ($i=0; $i<=10; $i++) { echo ($i.", "); } ?>

in this code the loop is not executed because the exit will terminate the execution of the code.

  17)

  

The rand function

The rand function allows you to print random numbers in a range chosen by us, in fact in the example

will be printed random numbers from 1 to 10, in the first function while the second will print numbers

from 4 to 50.

In the brackets the first number indicates the first number from where to start and then the smallest and

the second number after the comma the maximum number.

  <?php $num=rand(1,10); echo($num); echo("<br>"); $num_2=rand(4,50); echo($num_2); ?>

  18)

  

Pick up the date from the server

The function to get the date and date () we see in the example how it works.

  <?php echo date('d,m,Y'); ?>

  In the brackets we have inserted 3 letters easily understand that d stands for the day, m stands for

month and Y stands for year. Let's try to change the order of the letters and see how the result changes,

for example:

  <?php echo date('m,d,Y'); ?> In this case month, day and year will be printed.

  We can also assign the date to a variable by writing:

  $data=date('d,m,Y'); echo($data); ?>

  19) Verify a numeric value

  

To check if a value is numeric we use the function is_numeric () as in the following example:

  <?php $num=25; if (is_numeric($num)) { echo "il valore è un numero"; } else {

  } ?>

  20) The function strlen

  

The strlen () function returns the number of characters in a string as we see in the example:

  <?php $str="abcdef"; echo(strlen($str)); ?>

  21) The foreach cycle

  

With the foreach loop we can take a value contained in a series of objects or an array and then either

display the whole or perform a search.

  In the following example we show all the contents of an array:

  <?php $ar= array("Mario","Marco","Giovanni","Antonio", "Alfonso"); foreach($ar as $st) { echo($st); echo("<br>"); } echo("<br>"); ?> If we execute the code written above all the names inserted in the array will appear.

  Now we carry out a search to find a specific name:

  <?php $ar= array("Mario","Marco","Giovanni","Antonio", "Alfonso");

   foreach($ar as $st) { if ($st=="Giovanni") { echo ($st); } } ?>

  22) Instruction empty

  

With this function we can check whether a variable contains a value or after its declaration has not

yet been assigned a value, let's see how:

  <?php $nome;

   if (empty($nome)) { echo ("La variabile nome è vuota"); } else { echo("La variabile nome contiene: ". $nome); } ?>

  

Let's try to give it a value such as Mario and see how the result changes as the following example:

  <?php $nome = "Mario"; if (empty($nome)) { echo ("La variabile nome è vuota"); }

   { echo("La variabile nome contiene: ". $nome); } ?>

  23)

Functions

  

A function is a code that is written somewhere in the script and is only executed when the function is

called.

  

The code written in a function can contain anything like calculations, work with strings, update files,

databases and more.

  

A function can return a value or do something inside it, in which we can pass values or call it only to

make the code inside it run.

  However with some examples everything will be easier to understand.

Let's do a simple function that calculates, for example, the air of a triangle passing it two parameters

that is the base and the height of the geometric figure in question.

  <?php

  function calcola($base, $altezza) { $area=($base * $altezza)/2; return ($area); } ?> <?php $area_triangolo=calcola(3,4); echo ($area_triangolo); ?>

  

In the previous example the function calculates takes two parameters that are the base and the height

which are placed in the brackets when we call the function, and its result is inserted in the variable $

area_triangle. Let's do the same example with a function that does not return anything then:

  <?php function calcola ($base,$altezza) { $area=($base * $altezza)/2;

  } ?> <?php calcola(5,4); ?>

  In this case, the function does the same thing, however, it prints the result directly and therefore has no return value.

  

Let's take another example of a function that does not accept values and does not return any value, but

it shows a price list.

  <?php function listino_prezzi() { echo ("<table bgcolor='#33ddff' cellspacing='2' cellpading='2' border='1'>"); echo("<tr><td>Televisore </td> <td>marca XXXXX</td><td>42 pollici</td><td>Euro 200</td></tr>");

   pollici</td><td>Euro 150</td><tr>"); echo("<tr><td>Videocamera </td><td>marca BBBBBB</td><td>caratteristiche MMMMMM</td><td>Euro 300</td></tr>"); echo("<tr><td>Lettore MP3 </td><td>marca ZZZZZZ</td><td>8 Gb Stereo</td><td>Euro 80</td></tr></table>"); } ?> <?php listino_prezzi(); ?>

  

However the code was written with each instruction on a line as in the following figure, in fact for

reasons of space the code in the text went to the end.

  24)

Static Variables

  The static statement makes sure that when we have a variable in a script such as a function such a variable when the function finishes executing what the contained value should do for example as a result inserted into a variable we lose.

Often there may be cases in which the value of a result must be preserved and to make this happen we

must declare a static variable and therefore in its declaration make it precede the static keyword.

  Let's take some examples and see how it works right away.

  <?php function conta() { for ($i=0; $i<10; $i++) { $numero=0; $numero++; } echo ($numero); }

  ?> <?php conta(); conta(); ?>

  

In this example the function is called twice but will give the same value because it starts again from

scratch in the following example instead it maintains its value and is incremented further.

  <?php function conta() { for ($i=0; $i<10; $i++) { static $numero=0; $numero++; } echo ("<br>" . $numero); }

  ?> <?php conta(); conta(); ?>

  25) The constants

  

Una costante è una variabile che una volta che gli abbiamo assegnato un valore essa non può più

cambiare, vale sia per le stringhe che per altri valori numerici ecc.

  Il suo uso è molto semplice come nell'esempio che segue:

  <?php DEFINE("numero",10); DEFINE("nome","Marco"); echo (numero);

  echo("<br>"); echo (nome); ?>

  26) Create a folder

  

The function to create a folder is mkdir ("Folder name") and then insert the name of the folder to be

created between the brackets. But you have to be careful because if you try to create a folder that already exists and then as we know two folders with the same name can not exist in the same direction we get an error.

  

Then in the code that follows we see that we use a condition that verifies the existence of the folder

we want to create and then if the folder does not exist we are going to create otherwise the warning

appears.

  <?php if (!(is_dir("Foto"))) { mkdir("Foto");

  } else { echo("La cartella esite"); } ?>

  27) Delete a folder

  

Referring to the previous example, if we want to delete the created folder we will write:

<?php rmdir("Foto"); ?>

  28) Take the IP address

  

Taking a user's IP address is very simple: just apply the following code:

  <?php $ip = $_SERVER['REMOTE_ADDR']; echo(“il tuo IP è: “ . $ip); ?> We insert the IP into the variable $ ip, and then print it on the screen.

  29) Write and read files

  

To write to a file we use the fopen () function which opens a file if it exists or creates it if it does not

exist. In the brackets we insert the name of the file to be opened and the mode of access to the file,

that is, in read or write and read mode. Once the file is open, we will write it with fwrite (), and once

the writing operation is finished, we will close it as in the following example:

  <?php $txt = fopen("Testo.txt", "w+"); fwrite($txt, "Questa stringa viene scritta nel file"); fclose($txt); echo ("Scrittira completa con successo"); ?>

  

With w + the file is opened if it exists otherwise it is created and inserts the string, but if we want to

add a new string this option does not allow it every time the data is written replacing everything in

the file, if instead we want adding a new data without deleting what is already written we replace the

w + with "a".

  Let's run the code that follows and see that what we want to insert is added.

  <?php $txt = fopen("Testo.txt", "a+"); fwrite($txt, "Questa stringa viene aggiunta nel file"); fclose($txt);

  echo ("Scrittira completa con successo"); ?>

  

As we noted in the insertion, the string is inserted on the same line if instead we want to add to the

fwrite () characters to start a new line ie: fwrite ($ txt, "This string is added in the file". "\ R \ n "),

then when we're going to create a file in which we plan to add data in a new line and always add commands to create a new line.

  READ A FILE

To read a text file we use a while loop to scroll through the file to the end. And the fgets function to

read the lines as follows.

  <?php $leggi = fopen("Testo.txt","r"); while (!feof($leggi)) { echo fgets($leggi); echo("<br>"); } fclose($leggi); ?>

  30)

Check to see if a file exists

Now that we have seen how to create, read and write to a file, let's see how to check if a file exists.

  Then:

  <?php if (file_exists("Testo.txt")){ echo("Il file esiste"); } else { echo "Il file non esiste!"; } ?>

  

So from how you can easily guess the written code if the file exists we do an operation otherwise we

do another.

  31) Delete a file

  

To delete a file we simply use the unlink () statement in the brackets to insert the file name to be

deleted as follows:

  <?php if (file_exists("Testo.txt")) { unlink("Testo.txt"); echo("Il file è stato eliminato"); } else { echo "Attenzione: il file non esiste!"; } ?>

  

We check if the file exists and if it exists we delete it, otherwise we warn that the file does not exist.

  32)

Upload file

  

To transfer a file from a computer to the server we write two pages one in html and give it a name for

example formFile.html and the other a page in php we will call upload.php or a name you want.

  Nella pagina html inseriamo il form come segue:

  <html> <body> <form action='upload.php' enctype='multipart/form-data' method='post'> <input type='file' name='upload'/> <input type='submit' name='carica' value='Carica File'/>

  </form> </body> </html>

  This form assumes that the php page is called unpload.php otherwise in the action tag you have to

enter the name you have chosen for the page otherwise an error occurs because the page is not found.

  The PHP code is as follows:

  <?php if ($_POST['carica']){ move_uploaded_file($_FILES["upload"]["tmp_name"], $_FILES["upload"]["name"]); echo("File caricato "); } ?>

  

we can also check if the file already exists in the direction with the function we have seen previously

and therefore does not perform the operation, let's see how:

  if ($_POST['carica']) { $File=$_FILES["upload"]["name"]; if(file_exists($File)) { echo("Il file esiste già nella direzione"); exit; } move_uploaded_file($_FILES["upload"]["tmp_name"], $_FILES["upload"]["name"]); echo("File caricato "); } ?>

  33) Session variables

  

want to bring a value from one page to another we must use other methods and then session variables

which store the values on the server allowing to transport the values we enter from one side of the site to the other.

  Once a session variable has been created, we assign the value to it. This value keeps it stored until we close the browser.

  Their use is not complex at all. So to give an example we insert two pages we will call Session and Session2, logically they are names that we have put in this way to stay on the subject otherwise you can use any name for the pages that does not affect at all with the variables in question. On the first page we insert:

  <?php session_start(); $_SESSION["nome"]="Mario"; $_SESSION["cognome"]="Rossi"; echo($_SESSION["nome"] . " " . $_SESSION["cognome"]); echo("<br><br><a href='Session2.php'>vai al file 2</a>"); ?>

  

First we started the session with session_start () and then we can declare variables by giving them a

name and a random surname that we then print on video, and then inserted the link with the second page in which we will write:

  <?php session_start(); echo("Le variabili di sessioni contengono: " . $_SESSION["nome"] . " " . $_SESSION["cognome"]); ?>

  34) Cookie

  We have seen how to transport data from one part of a website with session variables to another, another way to store data in order to use it from any part of a website is to write cookies.

  Let's take an example so you can see practically everything.

  <?php

  setcookie("nome", "Mario", time() +3600); echo ("<a href='cok2.php'>vai a pagina 2</>"); ?>

  

The first parameter in brackets is the name of the cookie, the second is the value to be stored while

the third parameter sets the duration of the cookie in seconds, so the cookie we wrote after 3600 can

no longer display the data entered. At this point we see how to withdraw the entered value:

  <?php $nome = $_COOKIE["nome"]; echo $nome; ?> if we run this code, obviously after setting the cookie will display the string Mario.

  Obviously the instruction to read the cookie as above we can insert it in any page of the site. To delete a cookie, which in this case what we have created, we write the following:

  <?php setcookie("nome","",time() -3600); ?>

  

From how we see we assign a null string to the data and then set the time with a negative value.

  Example.

  <?php $testo="ABCDEF"; echo(strtolower($testo)); ?>

  36)

  Turn characters into uppercase To transform a string of uppercase characters we use the strtoupper () function Example.

  <?php $testo="abcdef"; echo(strtoupper($testo)); ?>

  37) Format a number

  

first is the number to be formatted, the second represents the number of decimal places, the third is the

decimal separator and the fourth separates every three digits of the whole part.

  Example:

  <?php $num=2300000; $num2 = number_format($num, 2, ',', '.'); echo($num2); ?>

  In this case the function returns the number so formatted 2,300,000.00, so that not only is it more professional to present a number as written above, but above all it is more readable.

  38)

Look for a value in an array make an example directly as it is a very simple instruction to use.

  <?php $persone=array("Marco", "Pietro", "Franco", "Roberto", "Giovanna"); if (in_array("Giovanna", $persone)) { echo("Nome trovato"); } else { echo("Esito ricerca negativo"); } ?>

  39) Instruction die

  

The die instruction is similar to exit, so when we want to interrupt the flow of the program we can use

that instruction.

  <?php echo ("Questa riga viene eseguita"); die("<br>Dopo di questa istruzione il flusso termina"); echo ("Codice seguente"); ?>

  40)

Interact with databases

  Now that we have learned a sufficient amount of commands to create a website, in this last part we see how to interact with a MySQL database, and then add, modify, delete and read data from a table of a DB. We begin to create a table in MySQL called Subscribers, as fields we enter ID, name, surname, city (we write city without accent) and insert fill some records so that in the first example we will see how to connect to a database and pull out some data. Done when said, in the code that follows we set up a connection to the DB and then we go to give some examples on how to get the data out.

  For those who have already been able to execute instructions in SQL everything will be easier, but

  Then:

  <?php $connection = mysql_connect('localhost','root','digilander'); mysql_select_db('DB2',$connection); $query = "SELECT * from Iscritti"; $risultato = mysql_query($query, $connection) or die("Errore..."); $numrows = mysql_num_rows($risultato); if ($numrows==0){ echo ("Attenzione nessun dato trovato"); } else { for($i=0; $i<$numrows; $i++){

  $idd=$campo[0]; $nome = $campo[1]; $cognome = $campo[2]; echo ("ID: <b> " .$idd ."</b>"); echo (" nome: <b> " . $nome . "</b>"); echo (" cognome: <b> " . $cognome . "</b><br/>"); } } ?>

  

In the first line I connect to the server by passing three parameters that are localhost, then enter the

username and password that we have set.

  

In the second line we insert the name of the Database, and the connection to the server, while in the

third line is an SQL statement that selects all the fields from the registered table, and that string is

passed to the mysql_query function with the respective connection. Or die etc. we insert it in such a way that if an error occurs we will notify and end the flow, if everything is OK, let's proceed.

  Then in the variable $ numrows we insert the number of rows and then check that it is non zero because if it is zero the table is empty, and so if it is not empty we continue.

  At this point, through a cycle, we scroll through the whole table, taking the data.

  41)

Look for a value in a tables of a DB

  We can do the research for any field, for example, looking for a registered name god, Marco, or for his surname Rossi, or for ID.

  

Usually in searches it is obvious to do a search for a field that is unique such as the tax code or the ID

field, while if I do a search by name in the result I will return all those with the same name, such as if

I do a searching in a table to find a car, it's better to do it for a license plate so that you can look for only what I want.

  In our example, to look for a subscriber in the table just change the SQL statement in the string $ query, in fact we try to write in the code that we wrote the following: $query=”Select * from iscritti where nome='Marco' “ All the members named Marco will come out.

  Example:

  <?php $connection = mysql_connect('localhost','root','digilander'); mysql_select_db('DB2',$connection);

  $risultato = mysql_query($query, $connection) or die("Errore..."); $numrows = mysql_num_rows($risultato); if ($numrows==0){ echo ("Attenzione nessun dato trovato"); } else { for($i=0; $i<$numrows; $i++){ $campo = mysql_fetch_row($risultato); $idd=$campo[0]; $nome = $campo[1]; $cognome = $campo[2]; echo ("ID: <b> " .$idd ."</b>"); echo (" nome: <b> " . $nome . "</b>"); echo (" cognome: <b> " . $cognome . "</b><br/>");

  } ?>

  Obviously if in the table you have not entered anyone named Marco you will see "Warning no data found".

  

Attention: To be noted in the SQL string the search string must be inserted between single quotes, if

the value is numeric then it must be left without single quotes as follows: $ query = "Select * from writing where ID = 1"; 42)

  

Insert a record

To insert a new record all the commands for the connection remain the same we can only change the

string of the SQL query, then using an insert statement of the SQL language as in the following example:

  <?php $connection = mysql_connect('localhost','root','digilander');

  mysql_select_db('DB2',$connection); $query = "INSERT INTO iscritti (nome, Cognome, Citta)

  VALUES('Giovanni','DiDonato','Empoli')"; if (!mysql_query($query, $connection)) { die('Errore: ' . mysql_error()); } echo "Record inserito"; mysql_close($connection); ?>

  43)

Change a record

  

Similarly, as for inserting a record, we only change the SQL command, and of course the notice of the

insertion result as the penultimate row.

  <?php $connection = mysql_connect('localhost','root','digilander'); mysql_select_db('DB2',$connection); $query = "UPDATE Iscritti SET nome='Vincenzo', cognome='Gargiulo', Citta='Torino' WHERE

  ID = 3"; if (!mysql_query($query,$connection)) { die('Errore: ' . mysql_error()); } echo "Record modificato"; mysql_close($connection); ?>

  44)

  Delete a record

Same thing to delete a record we change SQL command and warning string result.

  <?php $connection = mysql_connect('localhost','root','digilander'); mysql_select_db('DB2',$connection); $query = "DELETE FROM iscritti WHERE ID = 2"; if (!mysql_query($query,$connection)) { die('Errore: ' . mysql_error()); } echo "Record eliminato"; mysql_close($connection); ?>

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