Database Tutorial

<?php
  // This declares local variables.
  $a = true;   // This is a Boolean (bool) data type for true.
  $b = false;  // This is a Boolean (bool) data type for false.
  $c = "a";    // This is a full string data type.
  $d = "";     // This is an empty string data type.
  $e = 0;      // This is an integer value of zero.
  $f = -1;     // This is a negative integer value.
  $g = 1;      // This is a positive integer value.
  $h = null;   // This is a special null data type.
 
  // This compares a Boolean variable's truth.
  if ($a) {
    print "Variable [\$a][$a] is a [".gettype($a)."] and is true.\n"; }
  else {
    print "Variable [\$a][$a] is a [".gettype($a)."] and is false.\n"; }
 
  // This compares a Boolean variable's truth.
  if ($b) {
    print "Variable [\$b][$b] is a [".gettype($b)."] and is true.\n"; }
  else {
    print "Variable [\$b][$b] is a [".gettype($b)."] and is false.\n"; }
 
  // This compares a Boolean variable's truth.
  if ($c) {
    print "Variable [\$c][$c] is a [".gettype($c)."] and is true.\n"; }
  else {
    print "Variable [\$c][$c] is a [".gettype($c)."] and is false.\n"; }
 
  // This compares a Boolean variable's truth.
  if ($d) {
    print "Variable [\$d][$d] is a [".gettype($d)."] and is true.\n"; }
  else {
    print "Variable [\$d][$d] is a [".gettype($d)."] and is false.\n"; }
 
  // This compares a Boolean variable's truth.
  if ($e) {
    print "Variable [\$e][$e] is a [".gettype($e)."] and is true.\n"; }
  else {
    print "Variable [\$e][$e] is a [".gettype($e)."] and is false.\n"; }
 
  // This compares a Boolean variable's truth.
  if ($f) {
    print "Variable [\$f][$f] is a [".gettype($f)."] and is true.\n"; }
  else {
    print "Variable [\$f][$f] is a [".gettype($f)."] and is false.\n"; }
 
  // This compares a Boolean variable's truth.
  if ($g) {
    print "Variable [\$g][$g] is a [".gettype($g)."] and is true.\n"; }
  else {
    print "Variable [\$g][$g] is a [".gettype($g)."] and is false.\n"; }
 
  // This compares a Boolean variable's truth.
  if ($h) {
    print "Variable [\$h][$h] is a [".gettype($h)."] and is true.\n"; }
  else {
    print "Variable [\$h][$h] is a [".gettype($h)."] and is false.\n"; }
?>

Variable [$a][1] is a [boolean] and is true.
Variable [$b][] is a [boolean] and is false.
Variable [$c][a] is a [string] and is true.
Variable [$d][] is a [string] and is false.
Variable [$e][0] is a [integer] and is false.
Variable [$f][-1] is a [integer] and is true.
Variable [$g][1] is a [integer] and is true.
Variable [$h][] is a [NULL] and is false.

<?php
  // This declares local variables.
  $a = true;
  $b = true;
 
  // This compares two values.
  if ($a && $b) {
    print "Variable [\$a] and [\$b] are both true.\n"; }
  else {
    print "Variable [\$a] and [\$b] aren't both true.\n"; }
?>

Variable [$a] and [$b] are both true.

<?php
  // This declares local variables.
  $a = true;
  $b = false;
 
  // This compares two values.
  if ($a || $b) {
    print "At least variable [\$a] or [\$b] is true.\n"; }
  else {
    print "Neither variable [\$a] or [\$b] are true.\n"; }
?>

At least variable [$a] or [$b] is true.

<?php
  // This declares local variables.
  $a = true;
  $b = false;
 
  // This compares two values.
  if ($a || $b) {
    print "At least variable [\$a] or [\$b] is true.\n"; }
  if ($a && $b) {
    print "Both variable [\$a] or [\$b] are true.\n"; }
  else {
    print "Neither variable [\$a] or [\$b] are true.\n"; }
?>

At least variable [$a] or [$b] is true.

<?php
  // This declares local variables.
  $a = "One";
  $b = "One";
  $c = "Two";
 
  // This compares the values.
  if ($a == $b) {
    print "Variable [$a] matches variable [$b]"; }
  else {
    print "Variable [$a] doesn't match variable [$b]"; }
 
  // This compares the values.
  if ($a == $c) {
    print "Variable [$a] matches variable [$c]"; }
  else {
    print "Variable [$a] doesn't match variable [$c]"; }
?>

Variable [One] matches variable [One]
Variable [One] doesn't match variable [Two]

<?php
  // This declares local variables.
  $a = 1;
  $b = 1;
  $c = "1";
 
  // This compares values of the same data type.
  if ($a === $b) {
    print "Variable [$a] matches variable [$b]\n"; }
  else {
    print "Variable [$a] doesn't match variable [$b]\n"; }
 
  // This compares values of different data types.
  if ($a === $c) {
    print "Variable [$a] matches variable [$c]\n"; }
  else {
    print "Variable [$a] doesn't match variable [$c]\n"; }
?>

Variable [1] matches variable [1]
Variable [1] doesn't match variable [1]

  if ($a === (int) $c) {

<?php
  // Declare two Boolean variables.
  $a = true;
  $b = false;
 
  // Compare and process truth or falsity.
  ($a) ? print "Variable [\$a] is true.\n" : print "Variable [\$a] is false.\n";
  ($b) ? print "Variable [\$b] is true.\n" : print "Variable [\$b] is false.\n";
?>

Variable [$a] is true.
Variable [$b] is false.

<?php
  // Declare two variables.
  $a = true;
  $b = false;
 
  // Evaluate truth at multiple levels in a nested ternary operator.
  ($a) ? ($b) ? print "Variableis [\$a] and [\$b] are true.\n" : print "Variable [\$a] is true and [\$b] is false.\n" : print "Variable [\$a] and [\$b] are false.\n";
?>

<?php
  $a = true;
  $b = false;
 
  ($a) ?
       ($b) ?
              print "Variableis [\$a] and [\$b] are true.\n"
            : print "Variable [\$a] is true and [\$b] is false.\n"
       : print "Variable [\$a] and [\$b] are false.\n";
?>

Variable [$a] is true and [$b] is false.

<?php
  // Run script from command line.
  if (@$_SERVER["argv"]) {
    if ($_SERVER["argc"] >  1 ) {
      $salutation = $_SERVER["argv"][1];
      print "Query [$salutation]\n"; }}
 
  // Write a salutation switch statement.
  switch ($salutation) {
    case "Hello":
      print "Response [Hello User.]\n";
      break;
    case "Ciao":
      print "Response [Ciao Consumatore.]\n";
      break;
    default:
      print "Unknown Language.\n";
  }
?>

php Hello.php Ciao

Query [Ciao]
Response [Ciao Consumatore.]

<?php
  // Declare the magic number.
  $magic = 48;
 
  // Run script from command line.
  if (@$_SERVER["argv"]) {
    if ($_SERVER["argc"] >  1 ) {
      $guess = $_SERVER["argv"][1];
      print "Guess [$guess]\n"; }}
 
  // Ternary evaluation of input.
  (is_numeric($guess)) ? $guess = (int) $guess : $guess = 0;
 
  // Write a salutation switch statement.
  switch (true) {
    case (($guess >= 1) && ($guess <= 100)) && ($magic > $guess):
      print "Response [Low guess.]\n";
      break;
    case (($guess >= 1) && ($guess <= 100)) && ($magic < $guess):
      print "Response [High guess.]\n";
      break;
    case (($guess >= 1) && ($guess <= 100)) && ($magic == $guess):
      print "Response [Right guess.]\n";
      break;
    default:
      print "Response [Illegal guess.]\n";
  }
?>

<?php
  // Write a salutation switch statement.
  switch ($guess) {
    case (($guess >= 1) && ($guess <= 100)) && ($magic > $guess):
      print "Response [Low guess.]\n";
      break;