Slide môn học PHP session 6 handling databases with PHP

Connecting to a Database Uses three arguments to connect PHP to MySQL such as server host name, user name, user password  Connectivity of PHP to MySQL are divided into three steps:

Handling Databases with PHP

Session 15

 A variable can store only one value at a time

 An array is a variable that can store a set of values of the same data type

 We can combine the element values of two or more arrays This process is called as merging arrays

 In a single-dimensional array, the element includes only one

level of key value pairs

 In the multidimensional array, each element is an array Each

element requires an array name and multiple set of indices

 Multidimensional arrays are arrays that store another array within

 Database APIs

 Connecting to a database

 Data access functions

 Performing SQL queries using PHP

 Building HTML tables using SQL queries

Connecting to a Database

 Uses three arguments to connect PHP to MySQL

such as server host name, user name, user

password

 Connectivity of PHP to MySQL are divided into

three steps:

 Connection with the MySQL server

 Working with the databases

 Closing the database connection

Connection with the MySQL

Connection with the MySQL

 host_name – Specifies the server or the host name

 user_name – Specifies the user name of MySQL

 password – Specifies the password for the MySQL user

 link_id - Specifies the return value of the server

connection

Example for connection with the MySQL server

 For example, to connect PHP to MySQL server

Working with the Databases

 Establish a connection with the MySQL server

 Needs to perform basic PHP functions while

working with the database such as

 mysql_list_dbs()

 mysql_select_db()

 mysql_list_tables()

 mysql_num_rows()

mysql_list_dbs() function

 Displays all the databases present in the server

 Syntax for this function is:

mysql_select_db() function

 Selects a database from the server

 Syntax for this function is:

mysql_list_tables() function

 Displays the list of tables present in the selected database

 Syntax for this function is:

$result = mysql_list_tables(“database_name”,

$link_id);

Where,

 database_name – Specifies the database name

 link_id – Specifies the return value of the database

connection

 result – Stores the result of the function

mysql_num_rows() function

 Shows the number of rows present in the table

 Syntax for this function is:

$num_rows = mysql_num_rows($result);

Where,

 result – Specifies the argument taken for

displaying the number of rows

 num_rows – Stores the result of the function

Closing the connection

 Closes the connection with the MySQL server by using the mysql_close() function

 Syntax for this function is :

mysql_close($link_id);

Where,

 link_id - Specifies the return value of the server connection

Data Access Functions

 Uses MySQL functions in PHP for accessing data

from the tables of the database

 Data are accessed from the tables using the following

mysql functions Those are:

Example for d ata access functions

- I

 For example, to display the records of the table from the

USER database using the data access functions

Example for d ata access functions

die(“Unable to connect to database”);

$sqlquery = mysql_query(“SELECT * FROM

USER_DETAILS WHERE ADDRESS = ‘CALIFORNIA’”);

while($row = mysql_fetch_array($sqlquery))

{

echo “Name:”.$row[USER_NAME];

echo “Phone-No:”.$row[USER_PHONE_NO];

Example for data access functions

Performing SQL queries using

Performing SQL queries using

die(“Unable to connect to database”);

$sql_table=”CREATE TABLE USER_CONTACT(“.“USER_ID

INT NOT NULL PRIMARY KEY,“.“USER_NAME CHAR(25)

NOT NULL,“.“USER_EMAIL_ID CHAR(25)” “)”;

Building HTML tables using SQL

queries

 HTML supports the database application components for accessing the database

 For example, to display all the records of the

user_contact table from the user database by

using HTML table structure

Example for HTML tables using

Example for HTML tables using

SQL queries - II

if($mysql_db)

echo “<BR>Connected to the database”;

echo “<TABLE BORDER BGCOLOR=“WHITE”>”;

echo “<TR><TH> USER_ID <TH><TH> USER_NAME

<TH><TH> USER_EMAIL_ID </TH>”;

echo “<DBQUERY q> select * from user_contact”;

echo “<DBROW><TR><TD><? q.USER_ID></TD><TD><?

q.USER_NAME></TD><TD><? q.USER_EMAIL_ID>

</TD></TR>”;

echo “</DBQUERY>”;echo “</TR>”;echo “</TABLE>”;

?>

 Database APIs allows the developers to write

applications that are movable or easily accessible

between the database products

 Connection with the server is done by using