Connecting to the database_PHP tutorial

4. Database connection
Through PHP you can easily connect to the database, request data and display it in your web site, and even modify the data in the database. MySQL is a very popular database, and there are many tutorials on PHP and MySQL on the Internet. MySQL is free, which may attract many people. Due to its wide application, I don't want to go into details about the use of MySQL here. Oracle is widely used in enterprise applications, so we will use Oracle to introduce the connection between PHP and database. We will certainly not mention the design principles of the Oracle database, as this is beyond the scope of our discussion.
PHP provides two sets of functions to connect to Oracle, namely ORA_ and OCI functions. The ORA_ function is slightly outdated. The OCI function update is said to be better. The usage syntax of the two is almost the same. As mentioned before, your PHP installation options should support the use of both.
For more knowledge about installing an Apache server supporting PHP3 on Microsoft Windows platform and more knowledge about Oracle database, please consult the following URL: www.csoft.net/~vsbabu/articles/oraphp.html.

4.1 Connection

if ($conn=Ora_Logon("user@TNSNAME","password"))
{
echo "n";
}
else
{
echo "Failed :-( Could not connect to databasen";
}
Ora_Logoff($conn);
phpinfo();
?>
The above code uses the Oracle database name and user name defined by TNSNAME (specified in your tnsnames.ora file) and password to connect to the database. Based on a successful connection, the ora_logon function returns a non-zero connection ID and stores it in the variable $conn.

4.2 Query

Assume that the connection to the database is ready. Next we will come to the actual application of querying the database.The following code demonstrates a typical example of connecting and querying:
/*
* Connect to the database and execute the query
*/
function printoraerr($in_cur)
{
// Check whether Oracle has an error
// If there is an error, display it
// When the pointer is activated, call this function after each request for Oracle
if(ora_errorcode($in_cur))
echo "Oracle code - ".ora_error($in_cur)."n";
return;
}
/**main program*/
if (!($conn=ora_logon ("user@TNSNAME","password")))
{
echo "Connection to database failedn";
exit;
}
echo "Connected as connection - $conn
n";
echo "Opening cursor ...
n";
$cursor=ora_open($conn); printoraerr($cursor);
echo "Opened cursor - $cursor
n";
$qry="select user,sysdate from dual";
echo "Parsing the query $qry ...
n";
ora_parse($cursor,$qry,0); printoraerr($cursor);
echo "Query parsed
n";
echo "Executing cursor ...
n";
ora_exec($cursor); printoraerr($cursor);
echo "Executing cursor
n";
echo " Fetching cursor ...
n";
while(ora_fetch($cursor))
{
$user=ora_getcolumn($cursor,0); printoraerr($cursor);
$sysdate=ora_getcolumn($cursor,1); printoraerr($cursor);
echo " row = $user, $sysdate
n";
}
echo "Fetched all records
n";
echo "Closing cursor ...
n";
ora_close($cursor);
echo "Closed cursor
n ";
echo "Logging off from oracle...
n";
ora_logoff($conn);
echo "Logged off from oracle
n";
? >
(Translator’s Note: The above code segment lacks comments, please refer to the Oracle database function section of the PHP Manual)

4.3 Display results

The following code demonstrates how to query the database and Output the result:
function printoraerr($in_cur, $conn)
{
// Check if Oracle has an error
// If there is an error, display it
// This function is called after each Oracle request when the pointer is activated
// If it encounters an error, we exit immediately
if(ora_errorcode($in_cur))
{
echo "Oracle code - ".ora_error($in_cur)."
n";
ora_logoff($conn);
exit;
}
return;
}

function exequery($w_qry,$conn)
{
$cursor=ora_open($conn); printoraerr($cursor,$conn);
ora_parse($cursor,$w_qry,0); printoraerr($ cursor,$conn);
ora_exec($cursor); printoraerr($cursor,$conn);
$numrows=0;
$w_numcols=ora_numcols($cursor);
// display Head
echo "

".<br>ora_getcolumn($cursor,$i)."