lecture 7 - Introduction to MySQL with PHP.pptx

PHP MYSQL
COURSE INSTRUCTOR: Akram Ali Omar
Email: akram.ali.omar@gmail.com
Mobile: +255778695626
The State University Of Zanzibar 1
DINF - DCS 0212: Interactive Website Development

Opening and Closing a MySQL Connection
• Open a connection to a MySQL database server with the mysql_connect()
function
• The mysql_connect() function returns a positive integer if it connects to the
database successfully or FALSE if it does not
• Assign the return value from the mysql_connect() function to a variable that
you can use to access the database in your script

mysqli extension
• The mysqli extension features are dual interface.
• It supports the procedural and object-oriented programming paradigm
• Users migrating from the old mysql extension may prefer the procedural
interface.
• The procedural interface is similar to that of the old mysql extension.
• There are no significant performance differences between the two
interfaces. Users can base their choice on personal preference.
• In many cases, the function names differ only by prefix

Mixing styles
• It is possible to switch between styles at any time. Mixing both styles is not
recommended for code clarity and coding style reasons
• Bad coding style
$conn = new mysqli("example.com", "user", "password", "database");
if ($conn->connect_errno) {
echo "Failed to connect to MySQL: " . $conn->connect_error;
}
$res = mysqli_query($conn, "SELECT 'Possible but bad style.' AS _msg FROM
DUAL");
if (!$res) {
echo "Failed to run query: (" . $conn->errno . ") " . $conn->error;
}
if ($row = $res->fetch_assoc()) {
echo $row['_msg'];
}
?>

Connecting to MySQL
• Open a connection to a MySQL database server using
1. Using procedural interface
2. Using Object-oriented
<?php
$conn = mysqli_connect("example.com", "user", "password", "database");
if (mysqli_connect_errno($conn)) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
mysqli_close($conn);
?>
<?php
$conn = new Mysqli("example.com", "user", "password", "database");
echo "Failed to connect to MySQL: " . $conn->connect_error;
}
$conn->close();
?>

Reporting MySQL Errors
• Reasons for not connecting to a database server include:
 The database server is not running
 Insufficient privileges to access the data source
 Invalid username and/or password
• Use mysqli_errno()(procedural interface) and $conn-> errno(Object-
oriented) to returns the error code from the last attempted MySQL
function call or 0 if no error occurred
• Use mysqli_error() and $conn->error to return the error message of the
previous mysqli*() function 6

Suppressing Errors with the Error Control
Operator
• By default, functions in the mysqli package display errors and warnings as
they occur
• Use the error control operator (@) to suppress error messages
7

Terminating Script Execution
• The die() and exit() functions terminate script execution
• The die() version is usually used when attempting to access a data source
• Both functions accept a single string argument
• Call the die() and exit() functions as separate statements or by appending
either function to an expression with the or operator
8

<?php
$conn = @mysqli_connect("example.com", "user", "password", "database");
if (mysqli_connect_errno($conn)) {
die("Failed to connect to MySQL: " . mysqli_connect_error());
}
?>
<?php
$conn = @new mysqli("example.com", "user", "password", "database");
die("Failed to connect to MySQL: " . $conn->connect_error);
}
$conn->close();
?>

<?php
$conn = @mysqli_connect("example.com", "user", "password", "database")or
die("Failed to connect to MySQL: ". mysqli_connect_error() );
?>
<?php
$conn = @new mysqli("example.com", "user", "password", "database") or
die("Failed to connect to MySQL: " . $conn->connect_error);
$conn->close();
?>

Executing SQL Statements
• Use the mysqli_query(query) [procedural interface] and query(query)
[Object-oriented] functions to send SQL statements to MySQL
• The mysqli_query() and query(query) functions return one of three
values:
For SQL statements that do not return results (CREATE
DATABASE and CREATE TABLE statements) it returns a value of
TRUE if the statement executes successfully
11

Executing SQL Statements (continued)
• For SQL statements that return results (SELECT and SHOW
statements) the mysqli_query() and query() functions returns a result
pointer that represents the query results
 A result pointer is a special type of variable that refers to the
currently selected row in a resultset
• The mysqli_query() and query() functions return a value of FALSE for
any SQL statements that fail, regardless of whether they return results
12

Retrieving Records into an Indexed Array
• The mysqli_fetch_row()[procedural] and fetch_row()[Object oriented]
functions return the fields in the current row of a result set into an
indexed array and moves the result pointer to the next row

Retrieving Records into an Indexed Array and
display into HTML table
$SQLstring = "SELECT * FROM company_cars";
$QueryResult = @mysqli_query($SQLstring, $conn);
echo "<table width='100%' border='1'>";
echo "<tr><th>License</th><th>Make</th><th>Model</th>
<th>Mileage</th><th>Year</th></tr>";
while ($Row = mysqli_fetch_row($QueryResult)) {
echo "<tr><td>{$Row[0]}</td>";
echo "<td>{$Row[1]}</td>";
echo "<td align='right'>{$Row[3]}</td>";
echo "<td>{$Row[4]}</td></tr>"; }
echo "</table>";

$QueryResult = @$conn->query($SQLstring);
echo "<table width='100%' border='1'>";
echo "<tr><th>License</th><th>Make</th><th>Model</th>
<th>Mileage</th><th>Year</th></tr>";
while ($Row = $conn->fetch_row($QueryResult)) {
echo "<tr><td>{$Row[0]}</td>";
echo "<td align='right'>{$Row[3]}</td>";
echo "<td>{$Row[4]}</td></tr>"; }
echo "</table>";

16

Retrieving Records into an Associative Array
• The mysqli_fetch_assoc()[procedural] and fetch_assoc()[Object Oriented]
function returns the fields in the current row of a resultset into an associative
array and moves the result pointer to the next row
• The difference between mysqli_fetch_assoc() and mysqli_fetch_row() is that
instead of returning the fields into an indexed array, the mysqli_fetch_assoc()
function returns the fields into an associate array and uses each field name as
the array key
• You can also use mysqli_fetch_array()[procedural] or fetch_array()[Object
Oriented]which returns field in both indexing and associative array
17

Accessing Query Result Information
• The mysqli_num_rows()[function] function or $results-
>num_rows[Object oriented] returns the number of rows in a
query result
• The mysqli_num_fields() function returns the number of fields in
a query result
• Both functions accept a database connection variable as an
argument
18

Accessing Query Result Information (continued)
$QueryResult = @mysqli_query($SQLstring, $conn) or
die(mysqli_error());
echo "<p>Successfully executed the query.</p>";
$NumRows = mysqli_num_rows($QueryResult);
$NumFields = mysqli_num_fields($QueryResult);
if ($NumRows != 0 && $NumFields != 0){
echo "<p>Your query returned " .
mysqli_num_rows($QueryResult) . " rows and ".
mysqli_num_fields($QueryResult) . " fields.</p>";
}else{
echo "<p>Your query returned no results.</p>";}

$QueryResult = @$conn->query($SQLstring, $conn) or
die($conn->error);
echo "<p>Successfully executed the query.</p>";
$NumRows = $QueryResult->num_rows;
$NumFields = $QueryResult->num_fields;
if ($NumRows != 0 && $NumFields != 0){
echo "<p>Your query returned " . $QueryResult-
>num_rows. " rows and ". $QueryResult-> num_fields.
" fields.</p>";
}else{
echo "<p>Your query returned no results.</p>";}
$conn->close();

Closing Query Results
• When you are finished working with query results retrieved with the
mysqli_query() function, use the mysqli_free_result() function to close
the resultset
• To close the resultset, pass to the mysqli_free_result() function the
variable containing the result pointer from the mysqli_query() function
22

Inserting Record into Table
<?php
$conn = mysqli_connect("…","…","…,"…")or die('Could not
connect: ' . mysqli_error());
mysqli_query("INSERT INTO Persons (FirstName, LastName,
Age) VALUES ('Peter','Griffin','35')");
mysqli_query("INSERT INTO Persons (FirstName, LastName,
Age)
VALUES ('Glenn', ‘Brown', '33')");
?>
23

Delete Record
<?php
$sql = “DELETE FROM Persons WHERE FirstName = ‘Peter’
AND LastName = “Griffin’”);
mysqli_query($conn ,$sql);
?>
24

Update Record
25
<?php
$sql = “UPDATE Persons SET Age = ’36’ WHERE FirstName =
‘Peter’
AND LastName = “Griffin’”;
mysqli_query($sql, $conn)or die(mysqli_error());
?>

Using the mysqli_affected_rows() Function
• With queries that return results (SELECT queries), use the
mysqli_num_rows() function to find the number of records returned from
the query
• With queries that modify tables but do not return results (INSERT,
UPDATE, and DELETE queries), use the mysqli_affected_rows()
function to determine the number of affected rows
26

Using the mysql_affected_rows() Function
(continued)
$SQLstring = "UPDATE company_cars SET mileage=50112.3
WHERE license='AK-1234'";
$QueryResult = @mysqli_query($SQLstring, $conn)or
die(mysqli_error());
echo "<p>Successfully updated "
. mysqli_affected_rows($conn) . "
record(s).</p>";
27

Using the mysql_affected_rows() Function
(continued)
28

The State University Of Zanzibar 29

lecture 7 - Introduction to MySQL with PHP.pptx

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