PHP and MySQL

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PHP and MySQL

  1. 1. PHP and MySQL
  2. 2. PHP • Creates DYNAMIC web pages – HTML traditionally static – Contents regenerated every time visit or reload site • (e.g. can include current time) • PHP is a scripting language – Interpreted, not converted to binary executable files – (Dialogue for play interpreted by actors) – Strong at communicating with program components written in other languages • E.g. can embed PHP statements within HTML
  3. 3. PHP • Written as a set of CGI binaries in C in 1994 by R. Lerdorf – Created to display resume and collect data about page traffic, e.g. dynamic web pages – Personal Home Page tools publicly released 1995 – In 1998 became PHP: Hypertext Preprocessor • PHP parser with web server and web browser, model similar to MS ASP.NET, Sun JavaServer Pages
  4. 4. PHP • Used mainly in server-side scripting – Can be used from command line interface – Standalone graphical applications • Takes input from a file or stream containing text and PHP instructions • Outputs stream of data for display • PHP 4 – parser compiles input to produce bytecode – Zend engine (better performance than interpreted PHP 3) • PHP 5 – robust support for OO programming, better support for MySQL, support for SQLite, performance enhancements
  5. 5. PHP - specifics • Delimiters: <?php ?> or just <? ?> • PHP parses code within delimiters • Code outside delimiter sent to output, not parsed • Block comments /* */ • Inline comments // #
  6. 6. PHP vs. C++ • Similarities: – Compiled Language – Syntax nearly the same (For/While/If) – Requires semicolons after each statement ; – Assignment is right to left ($num = 56;) – Object-Oriented (Class support, inheritance, virtuals, polymorphism) – Functions! – Types are nearly the same (booleans, integers, strings, etc.)
  7. 7. PHP Versus C++ • Differences: – Variables begin with $ sign ($name = “John Doe”;) – No explicit declaration of variable types – Introduction of “lazy” functions (foreach, explode, mail) – No Function Overloading – “Hidden” functions-within-a-function – Compiled/interpreted during every page load – Documented! – Echo for output
  8. 8. PHP Versus C++ • Web Specific: – Cookies and “Sessions” – Dynamic HTML based on user-defined logic – Interact and process a form’s action – Process URL Parameters – Easy Database Integration – Cross-Site-Scripting (XSS) security hacks - taken care of by PHP 5 • Allows code injection by web users into web pages viewed by other users (e.g. phishing attacks)
  9. 9. Introducing/Review HTML • Hyper Text Markup Language: – Paired by angled brackets like XML (Ex. <font> </font>) – Can use a “WYSIWYG” (what you see is what you get) program such as FrontPage or Dreamweaver for development – Dynamic web languages such as PHP simply produces HTML
  10. 10. MySQL • MySQL queries same as SQL in Oracle • Except it’s freeware! • Has many of the same capabilities as traditional DBMSs – Multi-user, triggers, cursors, etc. – Doesn’t get performance advantages
  11. 11. MySQL commands mysql> CREATE TABLE table_name … INSERT Into table_name … mysql> LOAD DATA LOCAL INFILE “file_name” INTO TABLE table_name; mysql> file_name (containing a query) mysql> SELECT … FROM … WHERE … mysql> UPDATE … mysql> DELETE …
  12. 12. MySQL commands mysql> SHOW databases; mysql> USE db_name; mysql> SHOW tables; mysql> DESCRIBE table_name; mysql> create table … mysql> insert into table values (… mysql> select * from table_name;
  13. 13. Some php mysql functions • Mysql_connect (“localhost”, “login”, “password”) • Mysql_select_db (‘db_name’, $link_id) • mysql_query (string [, resource $link_id]) – Executes a query, place result in variable, like a cursor • mysql_error ( ) – Returns error message from previous sql operation • mysql_fetch_array ($result, how) – Traverses through cursor of query result – How is either mysql_assoc (use col. names) – Or mysql_num (use index number) or mysql_both • Mysql_num_fields
  14. 14. PHP In Action <? echo "Welcome to Vrbsky's DB"; // Connect to MySQL $link = mysql_connect("localhost", "svrbsky", “password"); if (!$link) {die('Not connected: '. mysql_error()); } // see if connected // Select DB will use $dbselected = mysql_select_db('cs457db', $link); // you may not have to do this mysql_select_db('cs457db') or die ('Could not select database'); // see if worked // Now the query $query = "Select * from testit"; // testit has 2 columns, id and age $result = mysql_query($query, $link); if (!$result) {die( 'Error in SQL: ' . mysql_error());} // process results using cursor while ($row = mysql_fetch_array($result)) { echo "<hr>"; //horizontal line echo "id: ". $row["id"] . "<br />"; echo "age: " . $row["age"] . "<br />"; } mysql_free_result ($result); mysql_close($link); // disconnecting from MySQL ?>
  15. 15. PHP and MySQL <?php $link=mysql_connect (“localhost”, “login”, “password”) mysql_select_db(‘db') or die('Cannot select database'); $query = 'CREATE TABLE contact( '. 'cid INT NOT NULL AUTO_INCREMENT, '. 'cname VARCHAR(20) NOT NULL, '. 'cemail VARCHAR(50) NOT NULL, '. 'csubject VARCHAR(30) NOT NULL, '. mysql_query($query, $link) or die (‘Cannot create table’); mysql_close($link); ?>
  16. 16. Access result row using col. name <?php $link=mysql_connect (“localhost”, “login”, “password”) mysql_select_db(‘db') or die('Cannot select database'); $query = "SELECT ssn, lname FROM employee"; $result = mysql_query($query, $link); while($row = mysql_fetch_array($result, MYSQL_ASSOC)) { echo “SSN :{$row[‘ssn']} <br>" . “Last : {$row[‘lname']} <br> <br>"; } // Alterntiavely can use index // while($row = mysql_fetch_array($result, MYSQL_NUM)) // { // echo “SSN :{$row[0]} <br>" . // “Last : {$row[1]} <br><br>"; // } mysql_close($link); ?>
  17. 17. Forms and input • Can use HTML to create forms • Users can input values to use as host variables in calls to mysql
  18. 18. Our setup • A machine for us to use PHP and MySQL • ip address of machine is: 130.160.47.111 • This is a linux machine – Emacs, vi (I haven’t used this since the ’80s) • You need to use SSH Secure Shell to Quick Connect to this machine • username is 1st name initial followed by last name • E-mail me requesting your password
  19. 19. Our setup • In order to use your account you must do: mkdir public_html chmod 755 public_html/ cd public_html • Use vi (or whatever) to create new PHP and HTML files in this directory
  20. 20. Our setup • Create/save a .php file using an editor • Sample program: <? php Echo “Hello World” ?> • To run it, from IE, type in ip address/~yourlogin/filename
  21. 21. MySQL • To start up MySQL type in: mysql –u your_login –D your_login –p It will then prompt you for your password • You automatically have a db created with the same name as your login, that is the –D parameter above
  22. 22. Example html and php <html> <head> </head> <center> <!-- The following line results in php code executed after input values in form -> <form method="post" action="example3.php"> <table> <tr><td align="left">Dnames</td> <td><input type="text" name="dname"></td> </tr> <tr><td align="left">Lname</td> <td><input type="text" name="lname" size="15"></td> </tr> <tr><colspan="2"> <p align="center"> <input type="submit" value="Enter record"> </td> </tr> </table> </form> </center> </html>
  23. 23. Html code • The previous code uses a form to ask for input values to a table • It will execute a php file after input values in form • Can use those values in php file, must use $_POST[‘var_name’]
  24. 24. PHP code • PHP code places values input from from into local variables • Connects to database • Inserts values into tables • Prints out values
  25. 25. PHP and MySQL <? // This is example3.php used in previous .htm code $link = mysql_connect("localhost", "svrbsky", “password"); if (!$link) {die('Not connected: '. mysql_error()); } mysql_select_db(‘svrbsky') or die ('Could not select database'); $dname= $_POST['dname']; $lname = $_POST['lname']; $query = "insert into testit2 values ('$dname', '$lname')"; $result = mysql_query($query); if (!$result) {die('SQL error: ' . mysql_error());} mysql_close($link); print "<html><body><center>"; print "<p>You have just entered this record<p>"; print "Dname: $dname<br>"; print "Lname: $lname"; print "</body></html>"; ?>
  26. 26. • Won’t this be fun for an assignment? • Lots of great links on the web to get into • How to determine what is error?
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