MYSQL - PHP Database Connectivity

Mrs. G.Chandraprabha,M.Sc.,M.Phil.,
Assistant Professor,
Department of Information Technology,
V.V.Vanniaperumal College for Women,
Virudhunagar.

MYSQL DATABASE
 world's most popular open source database
because of its consistent fast performance, high
reliability and ease of use
 Open Source License:- free
 GNU General Public License
 Free to modify and distribute but all modification must
be available in source code format
 Commercial:- not free
 Fully paid up professional support
• used by Google, Facebook Nokia, YouTube,
Yahoo!, Alcatel-Lucent, Zappos.com, etc.

BASIC DATABASE SERVER CONCEPTS
 Database runs as a server
 Attaches to either a default port or an administrator
specified port
 Clients connect to database
 For secure systems
 authenticated connections
 usernames and passwords
 Clients make queries on the database
 Retrieve content
 Insert content
 SQL (Structured Query Language) is the language used
to insert and retrieve content

• MySQL can be controlled through a
simple command-line interface; however,
we can use phpMyAdmin as an interface
to MySQL.
• phpMyAdmin is a very powerful tool; it
provides a large number of facilities for
customising a database management
system.

CONNECTING TO A MYSQL
• In order for our PHP script to access a
database we need to form a connection
from the script to the database
management system.
resourceId = mysql_connect(server, username, password);
• Server is the DBMS server
• username is your username
• password is your password

CONNECTING TO A MYSQL DBMS
• In order for our PHP script to access a
database we need to form a connection
from the script to the database
management system.
resourceId = mysql_connect(server, username, password);
• The function returns a resource-identifier type.
• a PHP script can connect to a DBMS anywhere in the world,
so long as it is connected to the internet.
• we can also connect to multiple DBMS at the same time.

SELECTING A DATABASE
• Once connected to a DBMS, we can
select a database.
mysql_select_db(databasename, resourceId);
• the resourceId is the one returned by mysql_connect()
• the function returns true if the selection succeeded; false,
otherwise.

EXAMPLE: CONNECT TO A DBMS AND
ACCESS DATABASE
<?php
$dbLocalhost = mysql_connect("localhost", "root", "")
or die("Could not connect: " . mysql_error());
mysql_select_db("glassesrus", $dbLocalhost)
or die("Could not find database: " . mysql_error());
echo "<h1>Connected To Database</h1>";
?>
• die() stops execution of script if the database connection
attempt failed.
• mysql_error() returns an error message from the previous
MYSQL operation.

READING FROM A DATABASE
• We can now send an SQL query to the
database to retrieve some data records.
resourceRecords = mysql_query(query, resourceId);
• the resourceId is the one returned by mysql_connect()
• the function returns a resource identifier to the returned data.

EXAMPLE: CONNECT TO A DBMS,
ACCESS DATABASE, SEND QUERY
<?php
$dbRecords = mysql_query("SELECT * FROM customers", $dbLocalhost)
or die("Problem reading table: " . mysql_error());
echo "<h1>Connected To Database</h1>";
?>
• the function will return a resource pointer (not the actual
data) to all the records that match the query.
• If all goes well, this script will output nothing on screen.

EXTRACT CONTENTS OF ONE RECORD
• We can now extract the actual data from
the resource pointer returned by
mysql_query().
fieldData= mysql_result(resourceRecords, row, field);
• the resourceRecords is the one returned by mysql_query()
• field – database field to return
• the function returns the data stored in the field.

EXAMPLE: CONNECT TO A DBMS,
ACCESS DATABASE, SEND QUERY
<?php
$strSurname = mysql_result($dbRecords, 0, "Surname");
echo "<p>$strSurname</p>";
?>
• the function will return a resource pointer (not the actual
data) to all the records that match the query.
• If all goes well, this script will output a surname on screen.

SQL STATEMENT
SELECT * FROM customers;
• Go and obtain from the database
• every field
• FROM the
• customers table

VIEWING A WHOLE RECORD
To view the whole record returned from
mysql_query(), we need another
function...
• resourceRecords – resource identifier returned from
mysql_query().
• it returns an array containing the database record.
array = mysql_fetch_row(resourceRecords)

EXAMPLE: DISPLAYING ALL CUSTOMER
RECORDS
<?php
require_once("database2.php");
while ($arrRecord = mysql_fetch_row($dbRecords)) {
echo "<p>" . $arrRecord[0] . " ";
echo $arrRecord[1] . " ";
echo $arrRecord[2] . " ";
echo $arrRecord[3] . "</p>";
}
?>
• The function returns false when the last record is returned; thus, stopping
the loop.
• Note, however, that the fields are referred to by using numbers – not very
easy to read and mistakes can be introduced.

LIMITING THE RECORDS RETURNED
SELECT Surname FROM customers
•Retrieves only the Surname field from the table customers

LIMITING THE RECORDS RETURNED
SELECT * FROM customers LIMIT 3,4
• Select a certain number of records form a table
• 3 is the starting row
• 4 is the number of records to be selected after the starting
row

SORTING RECORDS
The ORDER BY attribute can be used to sort
the order in which records are obtained.
• the ORDER BY attribute is followed by the data field on
which to sort the record
• DESC or ASC – from high to low, or from low to high
SELECT * FROM cutomers ORDER BY Surname DESC

INSERTING RECORDS
How to create new database records and insert
them into a table?
INSERT INTO table (field1, field2,...) VALUES (‘value1’, ‘value2’,...)
INSERT INTO table VALUES (‘value1’, ‘value2’,...)
•Alternatively, we have a simplified syntax:
$dbProdRecords = mysql_query("INSERT INTO products
VALUES ( ' ', 'Beer Mug', '600 ml Beer Mug', '100', '5.99')",
$dbLocalhost)

INSERTING RECORDS
Example15-14.php
<?php
// File: example15-15.php
$dbProdRecords = mysql_query("INSERT INTO products VALUES ('', 'Beer Mug', '600
ml Beer Mug', '100', '5.99')", $dbLocalhost)
or die("Problem writing to table: " . mysql_error());
$dbProdRecords = mysql_query("SELECT * FROM products", $dbLocalhost)
while ($arrProdRecords = mysql_fetch_array($dbProdRecords)) {
echo "<p>" . $arrProdRecords["Id"] . " ";
echo $arrProdRecords["Name"] . " ";
echo $arrProdRecords["Description"] . " ";
echo $arrProdRecords["Quantity"] . " ";
echo $arrProdRecords["Cost"] . "</p>";
}
?>

DELETING RECORDS
How to delete database records from tables?
DELETE FROM table WHERE field=‘value’
e.g.
$dbCustRecords = mysql_query("DELETE FROM customers
WHERE Id='3'", $dbLocalhost)
Note: If you have a relational database, you should tidy-up the other tables, based on
their connection with the record you’ve deleted.

DELETING RECORDS
How to delete database records from tables?
DELETE FROM table
This will delete all records from a table!
Note: back-up your database first!

AMENDING RECORDS
How to modify the contents of an existing
database record?
UPDATE table SET field=‘value1’, field=‘value2’...WHERE
field=‘value’
• requires you to specify the table, the list of fields with their
updated values, and a condition for selection (WHERE).

AMENDING RECORDS
Example15-14.php
<?php
// File: example15-18.php
$dbCustRecords = mysql_query("UPDATE products SET Description='250 ml Tall
Glass' WHERE Id='6'", $dbLocalhost)
or die("Problem updating table: " . mysql_error());
$dbProdRecords = mysql_query("SELECT * FROM products", $dbLocalhost)
while ($arrProdRecords = mysql_fetch_array($dbProdRecords)) {
echo "<p>" . $arrProdRecords["Id"] . " ";
echo $arrProdRecords["Name"] . " ";
echo $arrProdRecords["Description"] . " ";
echo $arrProdRecords["Quantity"] . " ";
echo $arrProdRecords["Cost"] . "</p>";
}
?>

AMENDING RECORDS
How to modify the contents of an existing
database record?
$dbCustRecords = mysql_query("UPDATE products SET Name='Beer
and Lager Glass' WHERE Name='Beer Glass'", $dbLocalhost)
•A number of records will be updated in this example.
Another Example:
UPDATE table SET field=‘value1’, field=‘value2’...WHERE
field=‘value’

COUNTING THE NUMBER OF RECORDS
How to count the number of records after
running a query?
$dbProdRecords = mysql_query("SELECT * FROM products",
$dbLocalhost)
$intProductCount = mysql_num_rows($dbProdRecords);
• you can also use the same function to determine if a record
exists.

MYSQL - PHP Database Connectivity

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