Getting good with MySQL part 2

1. 1
Internet Programming
Connecting PHP to a
Database

2. 2
Objectives
To construct programs that interact with
MySQL database.

3. TAB1033 - Internet Programming 3
How they are connected?

4. 4
MySQL
A Relational Database with a license,
allowing users to use it cost-free for
most non-commercial purposes.
A database choice for PHP developers.
Conceived as fast and flexible DBMS.

5. 5
Getting a Connection
Connect to any server that have permission to
use.
The mysql_connect function arranges the
communication link between MySQL and PHP.
The mysql_connect() function requires
three parameters:
 Server name : name or URL of the MySQL server
 Username : The username in MySql.
 Password : password identified by username

6. 6
Steps for Accessing MySQL
Database
1.Open a connection to MySQL
2.Select a particular database
$connection = mysql_connect(host,username, password);
$db = mysql_select_db( database_name , $connection );
$connection = mysql_connect("160.0.58.165", "stud0011",
"iiiiiiii");
$db = mysql_select_db("test" , $connection );

7. 7
Steps for Accessing MySQL
Database (cont.)
3. Access the tables in the database as
required
a. Create an SQL command string
containing your query.
$sql = "sql_command parameters";
$sql = "SELECT * FROM contact";

8. 8
Steps for Accessing MySQL
Database (cont.)
b. Execute the query
c. Deal with the result of the query
$result = mysql_query( $sql , $connection ) or
die("Couldn't execute query");
while($row = mysql_fetch_array($result)){ ... }
"SELECT * FROM contact";

9. 9
Creating an SQL Table
A bit tedious process
Easier if you could use phpMyAdmin
CREATE TABLE table_name
(
fieldname1 data_type(size);
fieldname2 data_type(size);
fieldname3 data_type(size);
.
.
.
fieldname-n data_type(size);
);

10. 10
SQL Commands
The main day-to-day queries used from
PHP scripts:
 INSERT INTO tablename ... VALUES ... ;
 REPLACE INTO tablename ... VALUES ... ;
 DELETE FROM tablename WHERE ... ;
 UPDATE tablename SET ... WHERE ... ;
 SELECT ... FROM tablename WHERE ...
ORDER BY... ;

11. 11
SQL Commands (cont.)
When writing SQL commands into PHP
scripts the usual problem of too many
quotes arises and 'internal' quotes (")
have to be escaped.
SQL query must finish with a semicolon,
as must a PHP script command.

12. 12
Examples of Built-In MySQL
Functions
 Returns an array that represents all the fields for a
row in the result set.
 Eg. $row = mysql_fetch_row($result)
 Moves the internal row pointer of a result to the
specified row, with rows counting from zero.
 Use this function with mysql_fetch_row to jump
to a specific row.
 Eg. $row = mysql_data_seek($result, 3)
array mysql_fetch_row(resource result)
boolean mysql_data_seek(resource result, integer row)

13. 13
Built-In MySQL Functions
array mysql_fetch_array(resource result,integer type)
Returns an array that represents all the fields for a row in the
result set.
Value is stored twice: Once indexed by offset starting from
zero, once indexed by the name of the field.
Eg. $row = mysql_fetch_array($result, 5)
array mysql_fetch_assoc(resource result)
Returns an array that represents all the fields for a row in the
result set.
Element is indexed by the names of the field only
Eg. $row = mysql_fetch_assoc($result)

14. 14
Examples
To create a web page that linked to sale
items record from a database.
Step 1: Create the table named catalog
in a database
CREATE TABLE catalog
(
ID INT(11) NOT NULL AUTO_INCREMENT,
Name CHAR(32),
Price DECIMAL(6,2),
PRIMARY KEY (ID)
);

15. 15
Example
Step 2 : Insert some items along with some
dummy prices.
INSERT INTO catalog (Name, Price) VALUES
(' Shampoo ' , 6.50),
(' Brush ', 2.00),
(' Conditioner ', 7.00),
(' Toothbrush ', 3.50),
(' Dental Floss ', 5.00);
SELECT * FROM catalog

16. 16
Example
Step 3: Write a PHP script to retrieve the data
from table and display them in HTML table
<?php
//connect to server, then test for failure
if(!($dbLink = mysql_connect(" localhost ", " user1", "")))
{
print("Failed to connect to database!<br>n");
print("Aborting!<br>n");
exit();
}
//select database then test for failure
if (!($dbResult = mysql_query("USE test", $dbLink)))
{
print("Cannot use the test database!<br>n");
print("Aborting!<br>n");
exit();
}
Database connection
No password
query

17. 17
Example
Creating HTML table from a query (cont.)
//get eveything from catalog table
$Query = "SELECT Name, Price " .
"FROM catalog " .
"ORDER BY Name ";
if(!($dbResult = mysql_query($Query, $dbLink)))
{
print("Could not execute query!<br>n");
print("MySQL reports: " . mysql_error() . !<br>n");
print("Query was: $Query<br>n");
exit();
}

18. TAB1033 - Internet Programming 18
Example
Creating HTML table from a query (cont.)
//start table
print("<table border = "0 ">n");
//create header row
print("<tr>n");
print("<td><b>Item</b></td>n");
print("<td><b>Price</b></td>n");
print("</tr>n");
//get each row
while ($dbRow = mysql_fetch_assoc($dbResult))
{
print("<tr>n");
print("<td>{$dbRow['Name']}</td>n");
print("<td align=right">{$dbRow['Price']}</td>n");
print("</tr>n");
}
//end table
print("</table>n");
?>
Fetch each row from the result set.
Expresses each column in the
result as an element of an
associative array.
Field name

19. 19
Output

20. 20
Drop Table
DROP TABLE IF EXIST catalog;

21. 21
Changing Data With the Update
Statement
UPDATE catalog
SET price = 10.00
WHERE name = 'Shampoo';
UPDATE table_name
SET fieldname1 = value
WHERE fieldname2 = value;

22. 22
Delete Data?
DELETE FROM catalog
WHERE name = 'Shampoo' AND price < 7.00 ;
DELETE FROM table_name WHERE fieldname2 = value;

23. 23
Summary
Database Connection
 For example:
 Host: 160.0.58.165
 Username:stud9988
 Password: mypass123
 Database Name : db9988
 Connection
$connection = mysql_connect("160.0.58.165",
"stud9988", "mypass123");

24. 24
Summary
Select database
$db = mysql_select_db("db9988" , $connection );
Select data from table student in database
db9988
$query = "SELECT id, name FROM student
WHERE id = ‘1234'";
$result = mysql_query($query,$connection)
or die("Couldn't execute query");
The result (output)
while($row = mysql_fetch_row($result)){
print($row[0]);//1234
print($row[1]);//Ali
}
id name
1234 Ali
6789 Mary
student

25. 25
Summary
Update data
$query1 = "UPDATE student SET name = 'Ahmad'
WHERE id = 1234";
• Delete data
$query2 = "DELETE FROM student WHERE name =
'Mary'";
Drop table
$query3 = "DROP TABLE IF EXIST student;";
id name
1234 Ali
6789 Mary
student