Everyday Italian Giada De Laurentiis Harry Potter J K. Rowling Learning XML Erik T. Ray CSCI 305 Introduction to Database Systems Professor Brian R. King Bucknell University – Computer Science Dept. PHP SELECT * FROM Students WHERE Grade >= 90 XML

Objective This is designed to teach you some bare essentials about PHP, and using it to connect to your DB

PHP Basics PHP – Hypertext Preprocessor Server-side scripting language Scripts reside between reserved PHP tags – Programmer can embed PHP in the HTML pages – Structurally similar to C/C++/Java syntax

PHP Basics Comments: – // –#–# – /* */ Variables: – All variables begin with $ – Case sensitive Type: – PHP is loosely typed. You do not need to declare variables before you add a value to it. PHP determines the type, depending on its initial value

PHP echo command echo is used to output the parameters passed to it Typical usage – send data to the client's web- browser

Echo example Notice how echo ‘5x5=$foo’ outputs $foo rather than replacing it with 25 Strings in single quotes (‘ ’) are not interpreted or evaluated by PHP This is true for both variables and character escape-sequences (such as “\n” or “\\”) <?php $foo = 25;// Numerical variable $bar = “Hello”;// String variable echo $bar;// Outputs Hello echo $foo,$bar;// Outputs 25Hello echo “5x5=”,$foo;// Outputs 5x5=25 echo “5x5=$foo”;// Outputs 5x5=25 echo ‘5x5=$foo’;// Outputs 5x5=$foo ?> <?php $foo = 25;// Numerical variable $bar = “Hello”;// String variable echo $bar;// Outputs Hello echo $foo,$bar;// Outputs 25Hello echo “5x5=”,$foo;// Outputs 5x5=25 echo “5x5=$foo”;// Outputs 5x5=25 echo ‘5x5=$foo’;// Outputs 5x5=$foo ?>

Arithmetic Operations $a - $b // subtraction $a * $b// multiplication $a / $b// division $a += 5// $a = $a+5 Also works for *= and /= <?php $a=15; $b=30; $total=$a+$b; echo $total; echo “ $total ”; // total is 45 ?> <?php $a=15; $b=30; $total=$a+$b; echo $total; echo “ $total ”; // total is 45 ?>

Concatenation Use a period to join strings into one. <?php $string1=“Hello”; $string2=“PHP”; $string3=$string1. “ ”. $string2; echo $string3; ?> <?php $string1=“Hello”; $string2=“PHP”; $string3=$string1. “ ”. $string2; echo $string3; ?> Hello PHP

Escaping the Character If the string has a set of double quotation marks that must remain visible, use the \ [backslash] before the quotation marks to ignore and display them. <?php $heading="\"Computer Science\""; echo $heading; ?> <?php $heading="\"Computer Science\""; echo $heading; ?> “Computer Science”

Control Structures if / else if / else while / do..while / for – foreach exists, but syntax is different switch / case / break / default boolean expressions All of the above are formed just like Java (same comparison and logical operators)

Arrays Three types: – Numeric array – An array with a numeric index – Associative array – Each ID key is associated with a value – Multidimensional array Dealing with arrays is easy. However, the library of functions for arrays is large.

Functions Functions MUST be defined before then can be called Function headers are of the format – Note that no return type is specified Unlike variables, function names are not case sensitive (foo(…) == Foo(…) == FoO(…)) function functionName($arg_1, $arg_2, …, $arg_n)

Functions example <?php // This is a function function foo($arg_1, $arg_2) { $arg_2 = $arg_1 * $arg_2; return $arg_2; } $result_1 = foo(12, 3);// Store the function echo $result_1;// Outputs 36 echo foo(12, 3);// Outputs 36 ?> <?php // This is a function function foo($arg_1, $arg_2) { $arg_2 = $arg_1 * $arg_2; return $arg_2; } $result_1 = foo(12, 3);// Store the function echo $result_1;// Outputs 36 echo foo(12, 3);// Outputs 36 ?>

Include Files include "opendb.php"; include "closedb.php"; The code in files will be inserted into current code. – Nice for modularizing and reusability

PHP Forms and User Input PHP $_GET and $_POST variables are used to retrieve information from forms, like user input NOTE: Any form element in an HTML page will automatically be available to your PHP scripts

Example form welcome.php

form.php <?php if ($_POST["submit"]) echo " You clicked Submit! "; else if ($_POST["cancel"]) echo " You clicked Cancel! "; ?> <?php if ($_POST["submit"]) echo " You clicked Submit! "; else if ($_POST["cancel"]) echo " You clicked Cancel! "; ?> What you see on your browser after clicking Submit

MySQL connection Best way is to just show by example…

connect.php <?php $user = "brk009"; $password = "……"; $database = "brk009_WWIIShipsDB"; $conn = mysql_connect("db.eg.bucknell.edu",$user,$password); if (!$conn) die("Cound not connect to database"); mysql_select_db($database) or die("Unable to select database"); $result = mysql_query("SHOW TABLES"); if (!$result) die("Query to show tables failed"); <?php $user = "brk009"; $password = "……"; $database = "brk009_WWIIShipsDB"; $conn = mysql_connect("db.eg.bucknell.edu",$user,$password); if (!$conn) die("Cound not connect to database"); mysql_select_db($database) or die("Unable to select database"); $result = mysql_query("SHOW TABLES"); if (!$result) die("Query to show tables failed");

connect.php (cont.) $num_row = mysql_num_rows($result); echo " Choose one table: "; echo " "; for($i = 0; $i < $num_row; $i++) { $tablename = mysql_fetch_row($result); echo " {$tablename[0]} "; } echo " "; mysql_free_result($result); mysql_close($conn); ?> $num_row = mysql_num_rows($result); echo " Choose one table: "; echo " "; for($i = 0; $i < $num_row; $i++) { $tablename = mysql_fetch_row($result); echo " {$tablename[0]} "; } echo " "; mysql_free_result($result); mysql_close($conn); ?>

showtable.php <?php $user = "brk009"; $password = "……"; $database = "brk009_WWIIShipsDB"; $table = $_POST["table"]; $conn = mysql_connect("db.eg.bucknell.edu",$user,$password); if (!$conn) die("Cound not connect to database"); mysql_select_db($database) or die("Unable to select database"); $result = mysql_query("SELECT * FROM {$table}"); if (!$result) die("Query to show tuples from table failed!". mysql_error()); <?php $user = "brk009"; $password = "……"; $database = "brk009_WWIIShipsDB"; $table = $_POST["table"]; $conn = mysql_connect("db.eg.bucknell.edu",$user,$password); if (!$conn) die("Cound not connect to database"); mysql_select_db($database) or die("Unable to select database"); $result = mysql_query("SELECT * FROM {$table}"); if (!$result) die("Query to show tuples from table failed!". mysql_error());

showtable.php (cont.) $fields_num = mysql_num_fields($result); echo " Table: {$table} "; echo " "; // Print headers for($i = 0; $i < $fields_num; $i++) { $field = mysql_fetch_field($result); echo " {$field->name} "; } echo " \n"; // Print data while($row = mysql_fetch_row($result)) { echo " "; foreach($row as $cell) echo " $cell "; echo " \n"; } mysql_free_result($result); mysql_close($conn); ?> $fields_num = mysql_num_fields($result); echo " Table: {$table} "; echo " "; // Print headers for($i = 0; $i < $fields_num; $i++) { $field = mysql_fetch_field($result); echo " {$field->name} "; } echo " \n"; // Print data while($row = mysql_fetch_row($result)) { echo " "; foreach($row as $cell) echo " $cell "; echo " \n"; } mysql_free_result($result); mysql_close($conn); ?>