Transcript Class 4:PHP & MySQL Integration

PHP+MySQL Integration
Connecting to databases
• One of the most common tasks when working
with dynamic webpages is connecting to a
database which holds the content of the page
• PHP has several libraries that allows for
communication with many different databases
• Some of these libraries have variations in the
commands
• We will be using the mysql library
• Most functions start with mysql_ and then the
name of the function
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Opening a connection
• You will need:
– The address to the database server
– A username with privileges to access the table you
require
– The username associated password
• Optionally:
– The name of the database you are connecting
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Connection Sequence
• mysql_connect(host, username, password):
returns a link to the host using username and
password authentication.
• Usage:
– $conn=mysql_connect(‘localhost’, ‘myusername’,’MyP455w0rd’)
• mysql_select_db(database,link): selects a database
from the connection in link
• Usage:
– mysql_select_db(‘db_name’,$conn);
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Executing Queries
• mysqli_query(link, query) is used to run a query on
the database server. Required the link and the query
string. Returns a result object.
• Usage:
– $result= mysql_query(“SELECT * from directory”, $conn);
• Queries can be constructed as strings and then the
string variable can be used on the mysql_query
command:
– $query="select * from directory";
– $result = mysql_query($query,$link) or die("could not
execute:".mysql_error());
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Working with the results
from the query
• Result sets are objects. They point to places in
memory where the query returned values exist
• Result set are NOT the individual rows from the query
• You can think of a result set as the TABLE that holds the
results
• You need to read the rows from that table individually
– $row=mysql_fetch_array($result);
• Using this function, the array returned can be either
numerically indexed or associative!
• If there are no more rows, the function returns FALSE
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Keeping it tidy
• Once you have completed your work with the
database, there are two things you should do:
– Free the results
– Close the connection to the server.
• Freeing the results can be optional: On closing the
connection, the results are automatically freed
• If you are planning to run further queries on the same
connection, it is good practice to free the previous
result set.
– mysql_free_result($result);
• To close the connection you use
– mysqli_close($conn);
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Working with databases –
key steps
• Design the DB – Create the DB on PHPMyAdmin
or MySQL command
• Design and Create the HTML
• Create a connection
• Select the table
• Run the query
• Verify Insert/Fetch the rows/Do other SQL
associated tasks
• Display Results as needed
• Close the connection
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Database Design
and Creation
Create database ‘hospital’, add a table ‘discharge’
with appropriate fields – patient id, name,
appointment type, admission ward, xray
examination, mri scan, cat scan, eye test, hearing
test, and date (to capture todays date)
hospital
discharge(patid,name,appointment,ward,xray,mri,c
scan,eye,hearing,date)
Data details
Field
Type
Comment
patid
int(11) NN AI PK
Primary Key Index
name
varchar(45)
Patient Full Name
appointment
varchar(11)
type of appointment:
GP, Specialist or Surgery
ward
char(2)
Admitted to ward? No, or ward A,B or C
xray
char(3)
x-rays taken? YES,NO
mri
char(3)
mri carried out? YES,NO
cscan
char(3)
CAT scan carried out? YES,NO
eye
char(3)
eye test carried out? YES,NO
hearing
char(3)
hearing test carried out? YES,NO
date
date
date of discharge: format YYYY-MM-DD as text
• Go ahead and create the database and table
using PHPMyAdmin or MySQL command
Prompt
Data capture form
link to php script file
use get to check form is working correct
post could also be used, user choice
<form action="process.php" method="get" name="discharge">
table name
Patient Name: <input type="text" name="name" /><br />
<hr />
Appointment type<br />
<select name="appointment">
<option value="GP">General Practicioner</option><br />
<option value="Specialist">Specialist</option><br />
<option value="Surgery">Surgery</option><br />
</select>
3 options for app type
Radio button
Admission to Wards:<br />
<label>
<input type="radio" name="ward" value="No" />
No Ward</label>
<br />
<label>
<input type="radio" name="ward" value="A" />
Ward A</label>
<br />
<label>
<input type="radio" name="ward" value="B" />
Ward B</label>
<br />
<label>
<input type="radio" name="ward" value="C" />
Ward C</label>
<br />
<hr />
4 options via radio
buttons, only one can
be selected on form
Checkboxes
Treatments Undertaken:<br />
<input type="checkbox" name="xray" value="yes" />X-Ray Treatment<br />
<input type="checkbox" name="mri" value="yes" />MRI Scan<br />
<input type="checkbox" name="cscan" value="yes" />CAT Scan<br />
<input type="checkbox" name="eye" value="yes" />Eye Test<br />
<input type="checkbox" name="hearing" value="yes" />Hearing Test<br />
<hr />
5 options, any can be selected on form
Submit/reset button
<input type="submit" value="Submit Form" />
<input type="reset" value="Reset Form" />
</form>
PHP-process.php
Open a new file, save as process.php, keep on same directory
as html file
<?php
$id = $_GET['patid'];
$name = $_GET['name'];
$app = $_GET['appointment'];
$ward = $_GET['ward'];
$string
single option data passing
$_POST option also viable, keep consistent with
previous use
Checkbox data
selection
checkboxes allow multiple options
if not checked, it will not pass
the parameter (not set)
if (isset($_GET['xray'])) {
$xray = $_GET['xray'];
} else {
$xray = "No";
}
if passed the default is set to ‘yes’
so if not passed, we need to assign
a value to the respective variable that
will go into the database
Note: This code needs to be repeated for every checkbox variable passed as a parameter
the variables used are:
$mri, $cscan, $eye, $hearing
print "Name:".$name."<br />";
print "Appointment:".$app."<br />";
print "Ward:".$ward."<br />";
print "X-Ray:".$xray."<br />";
print "MRI:".$mri."<br />";
print "CSCAN:".$cscan."<br />";
print "EYE:".$eye."<br />";
print "HEARING:".$hearing."<br />";
print used to check fields are being
passed and captured in the page
Database connection
$link = mysql_connect('localhost','student','student') or die(mysql_error());
mysql_select_db('hospital',$link);
Current date selection
This script demonstrates how the current date
can be obtained from the MySQL server using
the appropriate DATE query
$querydate = "SELECT CURDATE() as Today";
$result1 = mysql_query($querydate,$link) or die(mysql_error());
$row = mysql_fetch_assoc($result1);
$today = $row['Today'];
The parameter being queried (date)
does not have an index in the array,
so we need to use the alias “AS” to assign
an index that we can use to retrieve from
the result array
INSERT data
Query to insert all data from html form + date obtained from
previous query
$query = "INSERT INTO discharge VALUES
(NULL,'$name','$app','$ward','$xray','$mri','$cscan','$eye','$hearing','$today')";
$result = mysql_query($query,$link) or die(mysql_error());
$affected = mysql_affected_rows($link);
if ($affected >0) {echo "success";} else {echo "fail";}
detects affected rows in the query
in this case 1 row was INSERTED so
$affected=1 if the insert was successful
generates my-sql error causes
Selection to display all
This is another query to retrieve all the data
from the table discharge
$query3 = "SELECT * FROM discharge";
$result3 = mysql_query($query3,$link) or die(mysql_error());
$row3 = mysql_fetch_assoc($result3);
?>
Table design for results
<table width="200" border="1">
<tr>
<th scope="col">Patient ID</th>
<th scope="col">Patient Name</th>
<th scope="col">Appointment Type</th>
<th scope="col">Admitted to Ward</th>
<th scope="col">X-Ray</th>
<th scope="col">MRI</th>
<th scope="col">Cat Scan</th>
<th scope="col">Eye Test</th>
<th scope="col">Hearing Test</th>
<th scope="col">Date Discharged</th>
</tr>
Results
$row is an associative array containing the results,
the index of the array are the fields in the database
<tr>
<td><?php echo $row3['patid']; ?></td>
<td><?php echo $row3['name']; ?></td>
<td><?php echo $row3['appointment']; ?></td>
<td><?php echo $row3['ward']; ?></td>
<td><?php echo $row3['xray']; ?></td>
<td><?php echo $row3['mri']; ?></td>
<td><?php echo $row3['cscan']; ?></td>
<td><?php echo $row3['eye']; ?></td>
<td><?php echo $row3['hearing']; ?></td>
<td><?php echo $row3['date']; ?></td>
</tr>
</table>
do …. while loop
<?php do { ?>
<tr>
<td><?php echo $row3['patid']; ?></td>
<td><?php echo $row3['name']; ?></td>
<td><?php echo $row3['appointment']; ?></td>
<td><?php echo $row3['ward']; ?></td>
<td><?php echo $row3['xray']; ?></td>
<td><?php echo $row3['mri']; ?></td>
<td><?php echo $row3['cscan']; ?></td>
<td><?php echo $row3['eye']; ?></td>
<td><?php echo $row3['hearing']; ?></td>
<td><?php echo $row3['date']; ?></td>
</tr>
<?php } while ($row3=mysql_fetch_assoc($result3)); ?>
</table>
DO-WHILE Loop
needed to display
all the results of the database
Close connection
<?php
mysql_close($link);
?>
Places where
things can go wrong
• Creating a connection
– Server unreachable/offline
– Wrong username/password combination
• Selecting the table
– Table does not exist
– User without privileges for that table
• Running the query
– Syntax errors
– Empty result set
• Fetching results
– Misusing the array
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