Databases and PHP. Accessing databases from PHP

Transcription

1 Databases and PHP Accessing databases from PHP

2 PHP & Databases PHP can connect to virtuay any database There are specific functions buit-into PHP to connect with some DB There is aso generic ODBC functions that wi work with many other DB Before you can connect with PHP you must aready have a database instaed on the server machine have the proper extensions added to PHP have an account and password on the DB!

3 PHP & Databases These sides wi discuss the basic eements of database connectivity to mysql with PHP: How to connect to a server from PHP How to seect a database from PHP How to perform a query from PHP How to format and view resuts from PHP More information on controing mysql from PHP and on using other DB with PHP can be found at:

4 Basic PHP functions for using mysql mysq_connect() mysq_seect_db() Function Resut Opens a connection to the MySQL server. Requires a hostname, username, and password Seects a db on the MySQL server. mysq_query() mysq_fetch_array() mysq_resut() mysq_error() mysq_cose() Issues the SQL statement. Puts an SQL statement resut row into an array Gets singe eement resut data from a successfu query. Returns ameaningfu error message from MySQL. Coses a previousy opened connection to a MySQL server.

5 Connecting to a MySQL server Must know the name of the server and a vaid username and password. Syntax: $conn = mysq_connect( hostname or IP, username, password ) or die(mysq_error() ); die: A buit-in PHP function that prints an error message and exits the script. The use here, with the mysq_error() function, wi cause an error message to be printed. Usefu for debugging code. $conn: The mysq_connect function returns a pointer to a DB connection. You wi use this variabe ike a fie pointer Whenever you want to refer to this DB, use the $conn variabe

6 Connecting to MySQL II Modern object-oriented technique. Syntax: $conn = new mysqi($servername, $username, $password, $DBname); if ($conn->connect_error) { die("connection faied: ". $conn->connect_error); die: A buit-in PHP function that prints an error message and exits the script. wi cause an error message to be printed. $conn: Contains an object that contains a DB connection. You wi use this variabe ike a fie pointer Whenever you want to refer to this DB, use the $conn variabe

7 Seecting a DB Must have aready connected to mysql Now must choose the DB to use If you connected via Method II the DB is aready chosen Syntax: $db = mysq_seect_db( DBname, $conn) or die(mysq_error) ); Die: same use as before Must know the name of the database $conn is the pointer returned from the mysq_connect function

8 Issuing a SQL command Must have aready connected to mysql and seected a DB Now can issue any SQL command that you have permission to use. Two steps: Form the command into a string Use either the mysq_resut function or the mysq_fetch_assoc function.

9 Making a query Exampe: $sq = SELECT studentid, studentname FROM students ORDER BY studentid ASC ; $sq_resut = mysq_query($sq, $conn) or die(mysq_error() ); whie ($row = mysq_fetch_assoc($sq_resut)){ // process each row First ine creates an SQL query from the students tabe. Second ine sends the query to the mysq server represented by the variabe $conn The resut is paced in the $sq_resut variabe The whie statement processes the resuts mysq_fetch_array function returns the next row of the resut (stored in variabe $sq_resut) as an associative array

10 Making a query, method II Exampe: $sq = SELECT studentid, studentname FROM students ORDER BY studentid ASC ; $resut = $conn->query($sq); whie($row = $resut->fetch_assoc()) { // process each row First ine creates an SQL query from the students tabe. Second ine sends the query to the mysq server represented by the variabe $conn The resut is paced in the $resut object The whie statement processes the resuts fetch_assoc()) function returns the next row of the resut (stored in variabe $resut object) as an associative array

11 Processing a query Exampe (cont). You coud process the data in the whie oop ike this: echo <tabe> ; whie ($row = mysq_fetch_assoc($sq_resut)){ $funame = $row[studentname]; $fuid = $row[studentid]; echo <tr><td>$funame</td><td>$fuid</td></tr> ; echo </tabe> ;

12 Processing a query, method II Exampe (cont). You coud process the data in the whie o ike this: echo <tabe> ; if ($resut->num_rows > 0) { // output data of each row whie($row = $resut->fetch_assoc()) { echo "ID: ". $row["studentid"]. "Name: ".$row["studentname"]. ". $row["dorm"]. "<br>\n"; ese { echo "0 resuts";

13 Processing a query: addendum There is aso a php function mysq_fetch_array($sq_resut) This function does the same thing as mysq_fetch_assoc($sq_resut) Except that the resuting array can be indexed by either names or numbers. If you don t need to access the array by numbers, stick to using mysq_fetch_assoc($sq_resut)

14 Cosing a DB connection. Cosing a DB connection. A DB connection is automaticay cosed when a script ends. If your script is ong, however, it is good to cose the connection expicity. Reason: there are a imited number of connections that a MySQL server can make (depends on admin settings) Syntax: mysq_cose(); Or mysq_cose($conn); Exampe: $conn = mysq_connect( , testuser, conn!now ) or die(mysq_error() ); // a the code to do things with the database mysq_cose($conn);

15 Cosing a DB connect method II Cosing a DB connection. Syntax: $conn->cose(); Exampe: $conn = new mysqi($servername, $username, $password, $DBname); // a the code to do things with the database $conn->cose($conn);

16 Compete exampe: phpdb1.php Database: Ithaca Tabes in database: courses and students Courses tabe: students tabe: courseid Descript instrid Stuff Junk Stars 5654 studentid studentname dorm 1111 John Stanton 2222 Susan Russian House 3333 Gwendoyn Forbes 4444 Gabrie Wiiams

17 Compete exampe: phpdb1.php The next program accesses the students tabe from the Ithaca database Gets ony the studentid and studentname Prints the resuts into a tabe.

18 <?php Compete exampe: phpdb1.php // create connection echo "<htm>\n<head>\n<tite>our Students </tite>\n</head>\n<body bgcoor=yeow>\n"; echo "<p>\n<h1 stye='text-aign:center'>barr Schoo</h1>\n</p>\n<p>\n"; echo "<tabe>\n"; // create the connection and choose the DB $conn = new mysqi("ocahost", "barrg", "ithaca", "Ithaca"); // Check if connection was successfuy made if ($conn->connect_error) { die("connection faied: ". $conn->connect_error); echo "Connected successfuy"; Use your account name and password. The third parameter is the DB name. Use ocahost if you re connecting from the web, use the actua Linux server IP address (eg, ) if you re running this php script on a machine other than the Linux server

19 Compete exampe: phpdb1.php // create an SQL statement $sq = "SELECT studentid, studentname FROM students ORDER BY studentid ASC"; $resut = $conn->query($sq); // Check wether query worked; if it didn t there wi be 0 rows if ($resut->num_rows == 0) { die("connection faied: ". $conn->connect_error); whie ($row = $resut->fetch_assoc()){ $funame = $row['studentname']; $fuid = $row['studentid']; echo "<tr><td>$funame</td><td>$fuid</td></tr>\n"; echo "</tabe>\n"; echo "</body></htm>\n";?> When there are no more rows, the $resut- >fetch_assoc() wi return 0 which wi be put in $row. But the resut of the assignment statement is the vaue that is paced into the variabe $row. The number 0 is interpreted as fase so when there are no rows eft, the oop wi stop.

20 Compete exampe: the Junk Store A simpe store appication that uses a mysql database Two scripts junkstore.php Dispays the items for sae buystuff.php receives an order, updates the database, sends cost information back to the browser

21 Compete exampe: the Junk Store A simpe store appication that uses a mysql database Two scripts junkstore.php Dispays the items for sae buystuff.php receives an order, updates the database, sends cost information back to the browser

22 Compete exampe: the Junk Store Database: Junk Tabes in database: stuff stuff tabe: ID Name quant Price saeprice 1111 Watch Computer PDA Book Pickes

23 junkstore.php <?php // start the htm page echo "<htm>\n<head>\n<tite>john's Junk Jive</tite>\n</head>\n<body bgcoor=yeow>"; echo "<p><h1 stye='text-aign:center'>john's Junk Jive</h1></p><p>"; // create the connection $conn = new mysqi("ocahost", "barrg", "ithaca", "Junk"); // Check if connection was successfuy made if ($conn->connect_error) { die("connection faied: ". $conn->connect_error); // echo "Connected successfuy ;

24 junkstore.php (continued) // create an SQL statement $sq = "SELECT ID, name, quant, price, saeprice FROM stuff ORDER BY ID ASC"; $resut = $conn->query($sq); // Check wether query worked; if it didn t there wi be 0 rows if ($resut->num_rows == 0) { die("connection faied: ". $conn->connect_error); // Create the htm tabe echo "<tabe bgcoor=ightbue>\n"; echo "<form name=buystuff method=post action='buystuff.php'>\n"; echo "<tr>\n<th>item ID</th><th>Item Name</th><th>Quant Left</th><th>Price</th>"; echo "<th>sae Price</th><th>Number Ordered</th>\n</tr>\n"; This ine creates an htm form that wi ca buystuff.php when the submit button is cicked.

25 junkstore.php (continued) // get the info from the database // fetch_assoc gets the next row of the query resut whie ($row = $resut->fetch_assoc()){ $thename = $row['name']; // this gets the vaue associated with the name fied $theid = $row['id']; $thequant = $row['quant']; $theprice = $row['price']; $thesae = $row['saeprice']; // the variabe arow wi contain a string with a the htm tabe info. // note that the variabes that we created above are used to suppy the vaues from the DB $arow = "<tr>\n<td>$theid</td>\n<td>$thename</td>\n"; $arow = $arow."<td>$thequant</td>\n<td>$theprice</td>"; $arow = $arow."<td>$thesae</td>\n"; $arow = $arow."<td><input type=text size=20 name="; $arow = $arow.$thename." vaue=0></td></tr>\n"; echo $arow; echo "<input type=submit vaue='buy Now'>\n"; // this is the button echo "</form></tabe>";?>

26 buystuff.php <?php // create the web page echo "<htm>\n<head>\n<tite>john's Junk Jive</tite>\n</head>\n<body bgcoor=yeow>"; echo "<p><h1 stye='text-aign:center'>john's Junk Jive</h1></p><p>"; echo "<h2>thanks for buying the foowing stuff:</h2>\n</p>\n<p>"; // create a connection to the DB $conn = new mysqi("ocahost", "barrg", "ithaca", "Junk"); // Check connection if ($conn->connect_error) { die("connection faied: ". $conn->connect_error); // create an SQL statement $sq = "SELECT ID, name, quant, price, saeprice FROM stuff ORDER BY ID ASC"; $resut = $conn->query($sq); // make sure that the query got resuts if ($resut->num_rows == 0) echo "0 resuts";

27 buystuff.php (continue) // create the htm tabe echo "<tabe border=1 bgcoor=ightbue>\n"; echo "<tr>\n<th>item Name</th><th>Quant bought</th><th>your Cost</th></tr>"; whie ($row = $resut->fetch_assoc()){ $thename = $row['name']; $theid = $row['id']; $thequant = $row['quant']; $theprice = $row['price']; $thesae = $row['saeprice']; // foreach goes through each item received from web page that caed this script foreach ($_POST as $postname => $postvaue){ if ($postname == $thename && $postvaue <= $thequant && $postvaue > 0){ $totacost = 0; $thequant = $thequant - $postvaue; $totacost = $totacost + $postvaue * $thesae; $arow = "<tr stye='text-aign:center'>\n<td>$thename</td>\n"; $arow = $arow."<td>$postvaue</td>\n<td>\$$totacost</td>"; $arow = $arow."</tr>\n"; echo $arow; $dbupdate = "UPDATE stuff SET quant=$thequant WHERE ID=$theID"; $conn->query($dbupdate);

28 buystuff.php (continue) $conn->cose(); echo "</tabe>\n"; echo "<a href='junkstore.php'>shop More</a>\n"; echo "</body></htm>";?>