Database Processing with PDO

ISYS 475

PDO:http://net.tutsplus.com/tutorials/php/why-you-should-be-using-phps-pdo-

for-database-access/

• PDO – PHP Data Objects – is a database access layer providing a uniform method of access to multiple databases since PHP 5.1.

• Regardless of which database you're using, you use the same functions to issue queries and fetch data.

Database Support• PDO_DBLIB ( FreeTDS / Microsoft SQL Server / Sybase )• PDO_FIREBIRD ( Firebird/Interbase 6 )• PDO_IBM ( IBM DB2 )• PDO_INFORMIX ( IBM Informix Dynamic Server )• PDO_MYSQL ( MySQL 3.x/4.x/5.x )• PDO_OCI ( Oracle Call Interface )• PDO_ODBC ( ODBC v3 (IBM DB2, unixODBC and win32 ODBC) )• PDO_PGSQL ( PostgreSQL )• PDO_SQLITE ( SQLite 3 and SQLite 2 )• PDO_4D ( 4D )

A quick way to find out which drivers you have:

• print_r(PDO::getAvailableDrivers());

• Or

• http://localhost/xampp/– Phpinfo()

Connecting

Connecting Example: To MySQL

$dsn = 'mysql:host=localhost;dbname=custorders';$username = 'root';$password = '';$db = new PDO($dsn, $username, $password);

$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', '');

Or use one statement as:

Handle Exception• If there are any connection errors, a

PDOException object will be thrown. You may catch the exception if you want to handle the error condition.

catch (PDOException $e) { print "Error!: " . $e->getMessage() . "<br/>"; die();}

catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>";Exit(); }

Running SQL Statements with PDO

• SQL Select statement:– PDO::query — Executes an SQL Select statement,

returning a result set as a PDOStatement object • SQL Insert, Delete and Update statements:

– PDO::exec — Execute an SQL statement and return the number of affected rows

• Parameterized (Prepared) statement:– PDO::prepare — Prepares a statement for

execution and returns a PDOstatement object

Selecting Data with PDO query

• PDO::query — Executes an SQL Select statement, returning a result set as a PDOStatement object

• A nice feature of PDO::query() is that it enables you to iterate over the rowset returned by a successfully executed SELECT statement.

The PDOStatement classRepresents a prepared statement and, after the statement is executed, an associated result set

• PDOStatement::fetch — Fetches the next row from a result set• PDOStatement::fetchAll — Returns an array containing all of the

result set rows• PDOStatement::rowCount — Returns the number of rows

affected by the last SQL statement

Using PDOStatement’s fetch() method

• Query Returns a PDOStatement object, we can use PDOStatement object’s fetch() method to retrieve a row from the result set.

• Each row is represented as an array indexed by both column name and number.

• The return value of this function on success depends on the fetch type. In all cases, FALSE is returned on failure.

Types of arrays

• •Indexed arrays - Arrays with numeric index• •Associative arrays - Arrays with named keys

Example of indexed array:

<?php $cars=array("Volvo","BMW","Toyota");echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . "."; ?>

The index can be assigned automatically (index always starts at 0):

or the index can be assigned manually:

$cars[0]="Volvo"; $cars[1]="BMW"; $cars[2]="Toyota";

Example: Adding a new item

<?php $cars=array("Volvo","BMW","Toyota"); echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";$cars[3]="Ford";echo $cars[3]; ?>

Loop through an indexed array:Note: The count() function is used to return the

length (the number of elements) of an array:

<?php $cars=array("Volvo","BMW","Toyota"); $arrlength=count($cars);

for($x=0;$x<$arrlength;$x++) { echo $cars[$x]; echo "<br>"; }?>

Loop through indexed array using foreach

<?php $cars=array("Volvo","BMW","Toyota"); foreach($cars as $car) { echo $car; echo "<br>"; }?>

Associative Arrays

• Associative arrays are arrays that use named keys that you assign to them. They are an ordered map that associates values to keys:

• key => value

A value may be an array itself.Arrays and objects can not be used as keys.

Examples of creating an associative array:

$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");

$age['Peter']="35"; $age['Ben']="37"; $age['Joe']="43";

Or:

The named keys can then be used in a script:

<?php $age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43"); echo "Peter is " . $age['Peter'] . " years old."; ?>

Loop through associative array using foreach (access value only)

<?php $age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43"); foreach($age as $x) { echo $x ; echo "<br>"; }?>

Loop through an associative array and access the key and its value

<?php$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");

foreach($age as $x=>$x_value) { echo "Key=" . $x . ", Value=" . $x_value; echo "<br>"; }?>

Using while loop with fetch() to iterate over the result set<?phptry {$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $query="select * from customers"; $customers = $db->query($query);echo $customers->rowCount() . " rows returned."; echo "<table border=1><tr>" . "<th>CID</th>" . "<th>CName</th>" . "<th>City</th>" . "<th>Rating</th></tr>"; while ($customer = $customers->fetch()){ $cid=$customer["cid"]; //$customer is an array; field name is case sensitive or use index $Cname=$customer["cname"]; Or $customer[1] $City=$customer["city"]; $customer[2] $Rating=$customer["rating"]; $customer[3] echo "<tr><td>$cid</td>" . "<td>$Cname</td>" . "<td>$City</td>" . "<td>$Rating</td></tr>";}echo "</table>";}catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; }?>

PDOStatement::rowCount() • PDOStatement::rowCount() returns the number of rows

affected by the last DELETE, INSERT, or UPDATE statement executed by the corresponding PDOStatement object.

• If the last SQL statement executed by the associated PDOStatement was a SELECT statement, some databases may return the number of rows returned by that statement. However, this behaviour is not guaranteed for all databases and should not be relied on for portable applications.

Example of Using the query method and iterate over the result set using the foreach statement

<?phpTry {$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $query="select * from customers"; $customers = $db->query($query); //$customers is the result set of the PDOStatement echo "<table border=1><tr>" . "<th>CID</th>" . "<th>CName</th>" . "<th>City</th>" . "<th>Rating</th></tr>"; foreach ($customers as $customer){ $cid=$customer["cid"]; //field name is case sensitive $Cname=$customer["cname"]; $City=$customer["city"]; $Rating=$customer["rating"]; echo "<tr><td>$cid</td>" . "<td>$Cname</td>" . "<td>$City</td>" . "<td>$Rating</td></tr>";}echo "</table>";} catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; }?>

Example of Using fetchAll()<?php try{$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $query="select * from customers"; $customers = $db->query($query); $AllCustomers=$customers->fetchAll(); echo "<table border=1><tr>" . "<th>CID</th>" . "<th>CName</th>" . "<th>City</th>" . "<th>Rating</th></tr>"; foreach ($AllCustomers as $customer) { $cid=$customer["cid"]; //$customer is an array; field name is case sensitive $Cname=$customer[1]; $City=$customer[2]; $Rating=$customer[3]; echo "<tr><td>$cid</td>" . "<td>$Cname</td>" . "<td>$City</td>" . "<td>$Rating</td></tr>";}echo "</table>";} catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; }?>

Retrieve Record Based on Key:This form is used to enter CID

<body> <form name="getData" method="post" action="getCustomerData.php"> Enter CID: <input type="text" name="CID" value="" /><br><br> <input type="submit" value="Get Customer Data" name="btnSubmit" /> </form> </body>

Note: the use of foreach loop even though the statement returns at most one record

<?php try {$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $cid=$_POST['CID'];$query = "SELECT * FROM customers WHERE CID= '$cid'";$customers = $db->query($query);if ($customers->rowCount()==0)echo "Record does not exist!";else {foreach ($customers as $customer){$cid=$customer['cid'];$Cname=$customer['cname'];$City=$customer['city'];$Rating=$customer['rating'];echo "<p>CID: $cid </P>"; echo "<p>Cname: $Cname </P>"; echo "<p>City: $City </P>"; echo "<p>Rating: $Rating </P>" ;} } }catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; } ?>

Using fetch()<?php try {$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $cid=$_POST['CID'];$query = "SELECT * FROM customers WHERE CID= '$cid'";$customers = $db->query($query);if ($customers->rowCount()==0)echo "Record does not exist!";else {$customer=$customers->fetch();$cid=$customer['cid'];$Cname=$customer['cname'];$City=$customer['city'];$Rating=$customer['rating'];echo "<p>CID: $cid </P>"; echo "<p>Cname: $Cname </P>"; echo "<p>City: $City </P>"; echo "<p>Rating: $Rating </P>" ;} }catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; } ?>

Use One PHP Page for input and output

<?php if (!empty($_POST)) { $db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $cid=$_POST['CID'];$query = "SELECT * FROM customers WHERE CID= '$cid'";$customers = $db->query($query);if ($customers->rowCount()==0)echo "Record does not exist!";else {foreach ($customers as $customer){$cid=$customer['cid'];$Cname=$customer['cname'];$City=$customer['city'];$Rating=$customer['rating'];echo "<p>CID: $cid </P>"; echo "<p>Cname: $Cname </P>"; echo "<p>City: $City </P>"; echo "<p>Rating: $Rating </P>" ;} } }?> <form name="getData" method="post" action="getCustOnePage.php">Enter CID: <input type="text" name="CID" value="" /><br><br><input type="submit" value="Get Customer Data" name="btnSubmit" /></form>

Use PDO to create HTML controls

• Exampls:– Listbox– Link

Use PDO to create HTML listbox <?php $db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $query="select cid from customers"; $customerIDs = $db->query($query); echo "<form name='updateRating' method='post' action='getCustomerData.php'>"; echo "Select CID: <br>"; echo "<select name = 'CID'>"; foreach ($customerIDs as $customerID){ $cid=$customerID["cid"]; echo "<option value= $cid >$cid</option>"; } echo "</select><br><br>"; echo "<input type='submit' value='Show Customer Data' name='btnSubmit'/> </form>"; ?>

Use PDO to create links

<?php $db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $query="select cid from customers"; $customerIDs = $db->query($query); foreach ($customerIDs as $customerID) { $cid=$customerID["cid"]; echo "<a href='getCustomerDataGET.php?CID=$cid'>CID: $cid</a><br><br>"; } ?>

Program handling the link <?php try{$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $cid=$_GET['CID'];$query = "SELECT * FROM customers WHERE CID= '$cid'";$customers = $db->query($query);if ($customers->rowCount()==0)echo "Record does not exist!";else {$customer=$customers->fetch();$cid=$customer['cid'];$Cname=$customer['cname'];$City=$customer['city'];$Rating=$customer['rating'];echo "<p>CID: $cid </P>"; echo "<p>Cname: $Cname </P>"; echo "<p>City: $City </P>"; echo "<p>Rating: $Rating </P>" ;}}catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; } ?>

PDOStatement’s setFetchModemethod • Before calling fetch, it’s best to tell PDO how you’d like the data

to be fetched. You have the following options:• PDO::FETCH_ASSOC: returns an array indexed by column name• PDO::FETCH_BOTH (default): returns an array indexed by both

column name and number• PDO::FETCH_CLASS: Assigns the values of your columns to

properties of the named class. It will create the properties if matching properties do not exist

• PDO::FETCH_INTO: Updates an existing instance of the named class

• PDO::FETCH_NUM: returns an array indexed by column number• PDO::FETCH_OBJ: returns an anonymous object with property

names that correspond to the column names

Specifying a fetch mode, for example, PDO::FETCH_ASSOC

<?phptry {$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $query="select * from customers"; $customers = $db->query($query); $customers->setFetchMode(PDO::FETCH_ASSOC); echo "<table border=1><tr>" . "<th>CID</th>" . "<th>CName</th>" . "<th>City</th>" . "<th>Rating</th></tr>"; while ($customer = $customers->fetch()){ $cid=$customer["cid"]; //field name is case sensitive $Cname=$customer["cname"]; $City=$customer["city"]; $Rating=$customer["rating"]; echo "<tr><td>$cid</td>" . "<td>$Cname</td>" . "<td>$City</td>" . "<td>$Rating</td></tr>";}echo "</table>";} catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; } ?>

Use PDO::exec to run SQL Insert/Delete/Update Statements

• Execute an SQL Insert/Delete/Update Statement and return the number of affected rows.

New Customer Data Entry Form

<body> <form name="newCustomerForm" action="AddNewCustomer.php" method="POST"> CID: <input type="text" name="CID" value="" /><br><br> Cname: <input type="text" name="Cname" value="" /><br><br> City: <input type="text" name="City" value="" /><br><br> Rating: <input type="text" name="Rating" value="" /><br><br> <input type="submit" value="Add New Customer" name="btnSubmit" /> </body>

Code to Add a New Customer<?phptry{$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $cid=$_POST["CID"]; $cname=$_POST["Cname"]; $city=$_POST["City"]; $rating=$_POST["Rating"]; $queryINS = "insert into customers value('$cid','$cname','$city','$rating')";//$queryINS = "insert into customers value('" . $cid . "','" . $cname . "','" . $city// . "','" . $rating . "')";if( $db->exec($queryINS)==1) echo "Adding successful";else echo "Adding not successful";} catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; }?>

Using One PHP Program to Add a New Customer<?php if (!empty($_POST)){ try {$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $cid=$_POST["CID"]; $cname=$_POST["Cname"]; $city=$_POST["City"]; $rating=$_POST["Rating"]; $queryINS = "insert into customers value('$cid','$cname','$city','$rating')";if( $db->exec($queryINS)==1) echo "Adding succesful";else echo "Adding not succesful";} catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; } }?> <form name="newCustomerForm" action="addNewCustomer.php" method="POST"> CID: <input type="text" name="CID" value="" /><br><br> Cname: <input type="text" name="Cname" value="" /><br><br> City: <input type="text" name="City" value="" /><br><br> Rating: <input type="text" name="Rating" value="" /><br><br> <input type="submit" value="Add New Customer" name="btnSubmit" />

Form to enter CID for deletion

<body> <form name="deleteForm" action="deleteCustomer.php" method="POST"> Enter CID to delete: <input type="text" name="CID" value="" /><br> <input type="submit" value="Delete Customer" name="btnSubmit" /> </form> </body>

Code to delete a customer<?php

try{$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $cid=$_POST["CID"]; $queryDEL = "delete from customers where cid='$cid ‘”;if( $db->exec($queryDEL)==1) echo "Deleting succesful";else echo "Deleting not succesful";} catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; }?>

Example: Updating a customer’s rating field

• A php program to create a form with CID listbox and three radiobuttons to select new rating.

• A second php program is called to update the rating.

PHP program to create the form <?php $db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $query="select * from customers"; $customers = $db->query($query); echo "<form name='updateRating' method='post' action='execUpdateRating.php'>"; echo "Select CID: <br>"; echo "<select name = 'cid'>"; foreach ($customers as $customer){ $cid=$customer["cid"]; $cname=$customer["cname"]; $rating=$customer["rating"]; $cidnamerating=$cid . ": " . $cname .": " . $rating; echo "<option value= $cid >$cidnamerating</option>"; } echo "</select><br><br>"; echo "Select a new rating:<br> <input type = 'radio' name = 'newRating' value = 'A' checked = 'checked' /> A<br>"; echo "<input type='radio' name='newRating' value='B' /> B<br>"; echo "<input type='radio' name='newRating' value='C' /> C<br><br>"; echo "<input type='submit' value='Update Customer Rating' name='btnSubmit'/> </form>"; ?>

PHP program to update the rating<?php $db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $cid=$_POST["cid"]; $newRating=$_POST["newRating"]; $queryUpd="update customers set rating = '" . $newRating . "' where cid = '" . $cid . "'"; if( $db->exec($queryUpd)==1) echo "Updating succesful"; else echo "Updating not succesful"; ?>

Using Prepared (Parameterized) Statement

• A prepared statement or a parameterized statement is a precompiled SQL statement that can be executed multiple times by sending just the data to the server.

• It is used to execute the same statement repeatedly with high efficiency.

• You use a prepared statement by including placeholders in your SQL.

Benefits of Using Prepared statements • The query only needs to be parsed (or

prepared) once, but can be executed multiple times with the same or different parameters.

• The parameters to prepared statements don't need to be quoted (don’t need the quotation around the input variable); the driver automatically handles this. Hence no SQL injection will occur. Example:$stmt = $db->prepare("SELECT * FROM Customers where CID = ?");

SQL Injection Demo• On a web page that takes customer ID entered in

a textbox as input, then displays the customer’s data.

• Example: Retrieve all records:– In the textbox, enter:

‘ OR 1=1 OR CID = ‘

<form name="getData" method="post" action="demoSQLInjection.php"> Enter CID: <input type="text" name="CID" value="" /><br><br> <input type="submit" value="Get Customer Data" name="btnSubmit" /> </form>

<?phptry{$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $cid=$_POST['CID'];$query = "SELECT * FROM customers WHERE CID= '$cid'";echo "<table border=1><tr>" . "<th>CID</th>" . "<th>CName</th>" . "<th>City</th>" . "<th>Rating</th></tr>"; $customers = $db->query($query);foreach ($customers as $customer) { $cid=$customer['cid']; $Cname=$customer['cname']; $City=$customer['city']; $Rating=$customer['rating']; echo "<tr><td>$cid</td>" . "<td>$Cname</td>" . "<td>$City</td>" . "<td>$Rating</td></tr>"; } echo "</table>";}catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; } ?>

Using the PDO::prepare to create a prepared statement and returns a PDOstatement object

• PDO::prepare• Example:

– $stmt=$db->prepare($queryINS);

PDOStatement class Methods Related to Prepared Statement

• PDOStatement::bindParam — Binds a parameter to the specified variable name

• PDOStatement::bindValue — Binds a value to a parameter• PDOStatement::execute — Executes a prepared statement.

Returns TRUE on success or FALSE on failure.

Unnamed Placeholders as Parameters, ?

$queryINS = $db->("INSERT INTO customers values (?, ?, ?, ?)”);

Example:

Using Unnamed Placeholders:bindParam - Binds a parameter to the specified variable name

$stmt->bindParam(1, $cid); $stmt->bindParam(2, $cname); $stmt->bindParam(3, $city); $stmt->bindParam(4, $rating);

Execute(): Returns TRUE on success or FALSE on failure.

if($stmt->execute()) echo "Adding succesful";else echo "Adding not succesful";}

Example of using prepared statement<?phptry{$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $queryINS = "insert into customers value(?,?,?,?)"; $cid=$_POST["CID"]; $cname=$_POST["Cname"]; $city=$_POST["City"]; $rating=$_POST["Rating"]; $stmt=$db->prepare($queryINS);$stmt->bindParam(1, $cid); $stmt->bindParam(2, $cname); $stmt->bindParam(3, $city); $stmt->bindParam(4, $rating);

if($stmt->execute()) echo "Adding succesful";else echo "Adding not succesful";} catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; }?>

Example of using prepared statement<?phpTry {$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', '');$query = "SELECT * FROM customers WHERE CID= ?";$stmt = $db->prepare($query);$cid=$_POST["CID"];$stmt->bindParam(1, $cid);echo "<table border=1><tr>" . "<th>CID</th>" . "<th>CName</th>" . "<th>City</th>" . "<th>Rating</th></tr>"; if ($stmt->execute()) { while ($row = $stmt->fetch()) { $cid=$row["cid"]; //field name is case sensitive $Cname=$row["cname"]; $City=$row["city"]; $Rating=$row["rating"]; echo "<tr><td>$cid</td>" . "<td>$Cname</td>" . "<td>$City</td>" . "<td>$Rating</td></tr>"; } }echo "</table>";} catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; } ?>

If data is stored in an array

$data = array($cid, $cname, $city, $rating); $stmt=$db->prepare($queryINS);if($stmt->execute($data)) echo "Adding succesful";else echo "Adding not succesful";}

Code Example

<?phptry{$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $queryINS = "insert into customers value(?,?,?,?)"; $cid=$_POST["CID"]; $cname=$_POST["Cname"]; $city=$_POST["City"]; $rating=$_POST["Rating"]; $data = array($cid, $cname, $city, $rating); $stmt=$db->prepare($queryINS);if($stmt->execute($data)) echo "Adding succesful";else echo "Adding not succesful";} catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; }?>

Named Placeholders

$queryINS = "INSERT INTO customers values (:cid,:cname,:city,:rating)";

Using Named Placeholders<?phpTry {$db = new PDO('mysql:host=localhost;dbname=salesdb', 'root', ''); $queryINS = "INSERT INTO customers values (:cid,:cname,:city,:rating)"; $cid=$_POST["CID"]; $cname=$_POST["Cname"]; $city=$_POST["City"]; $rating=$_POST["Rating"]; $stmt=$db->prepare($queryINS);$stmt->bindParam(':cid', $cid); $stmt->bindParam(':cname', $cname); $stmt->bindParam(':city', $city); $stmt->bindParam(':rating', $rating); if($stmt->execute()) echo "Adding succesful";else echo "Adding not succesful";} catch (Exception $e) { $error_message = $e->getMessage(); echo "<p>Error message: $error_message </p>"; }?>