Monday, October 17, 2011

Using PHP with Oracle Database 11g


Overview

PHP is a popular web scripting language, and is often used to create database-driven web sites. This tutorial helps you get started with PHP and Oracle Database by showing how to build a web application and by giving techniques for using PHP with Oracle. If you are new to PHP, review the Appendix: PHP Primer to gain an understanding of the PHP language.

Prerequisites

Before starting this Oracle By Example, please have the following prerequisites completed:
1 .Install Oracle Database 11.2
2 .Start DRCP connection pooling:
sqlplus / as sysdba
execute dbms_connection_pool.start_pool();
execute dbms_connection_pool.restore_defaults();
3 .Create a user named PHPHOL with password of 'welcome'. Install Oracle's sample
HR schema and make the following changes:
 create sequence emp_id_seq start with 400;
   create trigger my_emp_id_trigger
   before insert on employees for each row
   begin
     select emp_id_seq.nextval into :new.employee_id from dual;
   end;
   /
   --
   -- Also to simplify the example we remove this trigger otherwise
   -- records can only be updated once without violating the
   -- PYTHONHOL.JHIST_EMP_ID_ST_DATE_PK constraint
   --

   drop trigger update_job_history;

   --
   -- Allow employees to be changed when testing the lab after hours.
   --
   drop trigger secure_employees;
4 .Install Apache and enable UserDir module for public_html
5 .Install PHP 5.3.3 with the OCI8 1.4 extension. In php.ini set:
oci8.connection_class = MYPHPAPP
6 .Extract these files to your $HOME location.

Using PHP OCI8 with Oracle Database 11g

This section of the tutorial shows how to use the PHP OCI8 extension directly with Oracle Database. Using the OCI8 extension directly gives programmers maximum control over application performance.

Creating a Standard Connection

To create a connection to Oracle that can be used for the lifetime of the PHP script, perform the following steps.
1 .
Review the code in $HOME/public_html/connect.php
<?php
// Create connection to Oracle
$conn = oci_connect("phphol", "welcome", "//localhost/orcl");
if (!$conn) {
   $m = oci_error();
   echo $m['message'], "\n";
   exit;
}
else {
   print "Connected to Oracle!";
}
// Close the Oracle connection
oci_close($conn);
?>
The oci_connect() function contains the username, the password and the connection string. In this case, Oracle's Easy Connect connection string syntax is used. It consists of the hostname and the DB service name.
The oci_close() function closes the connection. Any standard connections not explicitly closed will be automatically released when the script ends.
2 .
Open a Web browser and enter the following URL to display the output:
http://localhost/~phphol/connect.php
Show Screenshot for Step
"Connected to Oracle!" is displayed if the connection succeeds.
3 .Review the SQL in $HOME/public_html/usersess.sql
column username format a30
column logon_time format a18
set pagesize 1000 feedback off echo on

select username, to_char(logon_time, 'DD-MON-YY HH:MI:SS') logon_time
from v$session
where username is not null;

exit
This is a SQL script file that you run in SQL*Plus (Oracle's command-line SQL scripting tool). This SQL*Plus script shows the current database sessions, and what time they logged into the database.
4 .
Open a terminal window and enter the following commands to run the SQL script. Note that you could also execute the script in SQL Developer.
cd $HOME/public_html
sqlplus -l phphol/welcome @usersess.sql
Show Screenshot for Step
The SQL*Plus script lists the current database sessions. The only session shown is for SQL*Plus. The PHP connections from the oci_connect() function has been closed.
5 .
Edit $HOME/public_html/connect.php and change oci_connect() to use a persistent connectionoci_pconnect().
$conn = oci_pconnect("phphol", "welcome", "//localhost/orcl");
Reload the connect.php script in the browser. Now rerurn usersess.sql in SQL*Plus.
cd $HOME/public_html
sqlplus -l phphol/welcome @usersess.sql
Show Screenshot for Step
There should be two connected users. You may see more than two if you reloaded the page several times and Apache allocated different processes to handle the PHP script. By default, persistent connections stay open until the Apache process terminates. Subsequent PHP scripts can reuse the already opened connection, making them run faster.

Using Database Resident Connection Pooling

Database Resident Connection Pooling is a new feature of Oracle Database 11g. It is useful for short lived scripts such as typically used by web applications. It allows the number of connections to be scaled as web site usage grows. It allows multiple Apache processes on multiple machines to share a small pool of database server processes. Without DRCP, a non-persistent PHP connection must start and terminate a server process, and a persistent PHP connection keeps hold of database resources even when PHP is idle.
Below left is diagram of nonpooling. Every script has its own database server proces. Scripts not doing any database work still hold onto a connection until the connection is closed and the server is terminated. Below right is a diagram with DRCP. Scripts can use database servers from a pool of servers and return them when no longer needed.
Batch scripts doing long running jobs should generally use non-pooled connections.
This section of the tutorial shows how DRCP can be used by new or existing applications without writing or changing any application logic. Perform the following steps:
1 .
Check that php has oci8.connection_class set. Open a terminal window and execute the following command:
php -r 'echo ini_get("oci8.connection_class"), "\n";'
Show Screenshot for Step
The connection class tells the database server pool that connections are related. Session information (such as the default date format) might be retained between connection calls, giving performance benefits. Session information will be discarded if a pooled server is later reused by a different application with its own connection class name.
2 .
Review the code in $HOME/public_html/query_pooled.php
<?php

$c = oci_pconnect("phphol", "welcome", "//localhost/orcl:pooled");

$s = oci_parse($c, 'select * from employees');
oci_execute($s);
oci_fetch_all($s, $res);
echo "<pre>\n";
var_dump($res);
echo "</pre>\n";

?>
Compare this code to the code in $HOME/public_html/query_nonpooled.php
<?php

$c = oci_pconnect("phphol", "welcome", "//localhost/orcl");
$s = oci_parse($c, 'select * from employees');
oci_execute($s);
oci_fetch_all($s, $res);
echo "<pre>\n";
var_dump($res);
echo "</pre>\n";

?>
The only difference is the ":pooled" in the Easy Connect connection string in query_pooled.php.
3 .
To run the scripts, the Apache Benchmark tool is used. This command repeatedly loads a web page, measuring its performance. From a terminal window, execute the following:
ab -c 150 -t 30 http://localhost/~phphol/query_pooled.php
Show Screenshot for Step
Show Screenshot for Step
The above command sends Apache 150 concurrent requests for the script, repeatedly for 30 seconds.

4 .
Now look at the number of database connections open. Open another terminal window, execute the following:
sqlplus phphol/welcome
select username, program from v$session where username = 'PHPHOL';
Show Screenshot for Step
The default DRCP pool MAXSIZE is 40. You see up to 40 connections with PHPHOL username, depending on how many Apache processes handled the 'ab' requests. You may also need to execute the query while 'ab' is running to see the pooled servers working.
Oracle manages the DRCP pool, shrinking it after a specified timeout.
5 .
Now, you will run the same command except run the non-pooled script to compare the difference. From a terminal window, execute the following:
ab -c 150 -t 30 http://localhost/~phphol/query_nonpooled.php
Show Screenshot for Step
Show Screenshot for Step
6 .
Now look at the number of database connections open. Open another terminal window, execute the following:
sqlplus phphol/welcome
select username, program from v$session where username = 'PHPHOL';
Show Screenshot for Step
Many more rows than previously are returned. The rows with
httpd@localhost.localdomain (TNS V1-V3)
correspond to a running Apache process holding a database connection open. For PHP, Apache runs in a multi-process mode, spawning child processes each of which can handle one PHP script. Depending how Apache allocated these processes to handle the "ab" requests, you may see a varying number of rows in V$SESSION.
Compare the number of requests completed in each run. You might want to run each script a few times to warm up the caches.
Performance of the scripts is roughly similar. For the small works loads used in these two files, the tiny overhead of the handoff of pooled servers might make query_pooled.php a little slower than query_nonpooled.php. But the non-pooled script causes every single Apache process to open a separate connection to the database. For larger sites, or where memory is limited, the overall benefits of DRCP are significant.

Fetching Data

A common task when developing Web applications is to query a database and display the results in a Web browser. There are a number of functions you can use to query an Oracle database, but the basics of querying are always the same:
1.Parse the statement for execution.
2.Bind data values (optional).
3.Execute the statement.
4.Fetch the results from the database.
To create a simple query, and display the results in an HTML table, perform the following steps.
1 .
Review the code in $HOME/public_html/query.php
<?php

// Create connection to Oracle
$conn = oci_connect("phphol", "welcome", "//localhost/orcl");

$query = 'select * from departments';
$stid = oci_parse($conn, $query);
$r = oci_execute($stid);

// Fetch each row in an associative array
print '<table border="1">';
while ($row = oci_fetch_array($stid, OCI_RETURN_NULLS+OCI_ASSOC)) {
   print '<tr>';
   foreach ($row as $item) {
       print '<td>'.($item !== null ? htmlentities($item, ENT_QUOTES) : '&nbsp').'</td>';
   }
   print '</tr>';
}
print '</table>';

?>
The oci_parse() function parses the statement.
The oci_execute() function executes the parsed statement.
The oci_fetch_array() function retrieves a row of results of the query as an associative array, and includes nulls.
The htmlentities() function escapes any text resembling HTML tags so it displays correctly in the browser.
2 .
From your Web browser, enter the following URL to display the output:
http://localhost/~phphol/query.php
Show Screenshot for Step
The results of the query are displayed in the Web browser.
The OCI_ASSOC parameter fetches the row as an associative arrary of column names and column data.

Alternatively, the OCI_NUM parameter can be passed to oci_fetch_array() to fetch the row as a numeric array.

Using Bind Variables

Bind variables enable you to re-execute statements with new values, without the overhead of reparsing the statement. Bind variables improve code reusability, and can reduce the risk of SQL Injection attacks.
To use bind variables in this example, perform the following steps.
1 .
Review the code in $HOME/public_html/bind.php
<?php

function do_fetch($myeid, $s)
{
  // Fetch the results in an associative array
  print '<p>$myeid is ' . $myeid . '</p>';
  print '<table border="1">';
  while ($row = oci_fetch_array($s, OCI_RETURN_NULLS+OCI_ASSOC)) {
    print '<tr>';
    foreach ($row as $item) {
      print '<td>'.($item?htmlentities($item):'&nbsp;').'</td>';
    }
    print '</tr>';
  }
  print '</table>';
}

// Create connection to Oracle
$c = oci_connect("phphol", "welcome", "//localhost/orcl");

// Use bind variable to improve resuability, 
// and to remove SQL Injection attacks.
$query = 'select * from employees where employee_id = :eidbv';
$s = oci_parse($c, $query);

$myeid = 101;
oci_bind_by_name($s, ":EIDBV", $myeid);
oci_execute($s);
do_fetch($myeid, $s);

// Redo query without reparsing SQL statement
$myeid = 104;
oci_execute($s);
do_fetch($myeid, $s);

// Close the Oracle connection
oci_close($c);

?>
2 .
From your Web browser, enter the following URL to display the output:
http://localhost/~phphol/bind.php
Show Screenshot for Step
The $myeid variable is bound to the :eidbv bind variable so when the query is re-executed the new value of$myeid is passed to the query. This allows you to execute the statement again, without reparsing it with the new value, and can improve performance of your code.
If you don't see the returned rows, you may have deleted these employees in the web application part of the tutorial. Use SQL*Plus to query the EMPLOYEE_ID column of the EMPLOYEES table, and edit bind.php to use IDs that exist in the table.

Creating Transactions

When you manipulate data in an Oracle Database (insert, update, or delete data), the changed or new data is only available within your database session until it is committed to the database. When the changed data is committed to the database, it is then available to other users and sessions. This is a database transaction.

By default, when PHP executes a SQL statement it automatically commits. This can be over-ridden, and the oci_commit() and oci_rollback() functions used to control transactions. At the end of a PHP script, any uncommitted data is rolled back.

Committing each change individually causes extra load on the server. In general you want all or none of your data committed.  Doing your own transaction control has performance and data-integrity benefits.

To learn about transaction management in PHP with an Oracle database, perform the following steps.
1 .
Start SQL*Plus and create a new table:
sqlplus phphol/welcome
create table mytable (col1 date);
Show Screenshot for Step
2 .
Review the code in $HOME/public_html/trans_rollback.php
<?php

$conn = oci_connect("phphol", "welcome", "//localhost/orcl");

// PHP function to get a formatted date
$d = date('j:M:y H:i:s');

// Insert the date into mytable
$s = oci_parse($conn,
  "insert into mytable values (to_date('" . $d . "', 
         'DD:MON:YY HH24:MI:SS'))");

// Use OCI_DEFAULT to insert without committing
$r = oci_execute($s, OCI_DEFAULT);

echo "Previous INSERT rolled back as no commit is done before script ends";

?>
The OCI_DEFAULT parameter overrides the basic behavior of oci_execute().
3 .
From your Web browser, enter the following URL to display the output:
http://localhost/~phphol/trans_rollback.php
This script inserts a row into the table.
Show Screenshot for Step
4 .
Because there is no automatic or explicit commit, the data is rolled back by PHP when the script finishes. To see that the data has not been committed, query the table to see if there are any inserted rows. From your SQL*Plus session, enter the following commands to select any rows from the mytable table:
select to_char(col1, 'DD-MON-YY HH:MI:SS') time from mytable;
Show Screenshot for Step

5 .
Review the code in $HOME/public_html/trans_autocommit.php
<?php

$conn = oci_connect("phphol", "welcome", "//localhost/orcl");

// PHP function to get a formatted date
$d = date('j:M:y H:i:s');

// Insert the date into mytable
$s = oci_parse($conn,
  "insert into mytable values (to_date('" . $d . "',
          'DD:MON:YY HH24:MI:SS'))");

// Insert & commits
$r = oci_execute($s);

// The rollback does nothing: the data has already been committed
oci_rollback($conn);

echo "Data was committed\n";

?>
This script differs from trans1.php in that there is no OCI_DEFAULT when the data is inserted.  This means the new data is committed by the oci_execute() call.
6 .
From your Web browser, enter the following URL to display the output:
http://localhost/~phphol/trans_autocommit.php
Show Screenshot for Step
The data is now committed.
7 .
From your SQL*Plus session, enter the following command to select any rows from the mytable table:
select to_char(col1, 'DD-MON-YY HH:MI:SS') time from mytable;
Show Screenshot for Step
If you reloaded the PHP script more than once, a row from each execution is inserted.
8 .
You can compare the performance difference between committing each row individually versus at the end of the transaction.
To test the difference, review the code in $HOME/public_html/trans_time_autocommit.php
This code commits on each insert.
<?php

function do_insert($conn)
{
  $stmt = "insert into mytable values (to_date('01-JAN-08 10:20:35', 
       'DD:MON:YY HH24:MI:SS'))";
  $s = oci_parse($conn, $stmt);
  $r = oci_execute($s);  // automatically commit
}
function do_row_check($conn)
{
  $stid = oci_parse($conn, "select count(*) c from mytable");
  oci_execute($stid);
  oci_fetch_all($stid, $res);
  echo "Number of rows: ", $res['C'][0], "<br>";
}
function do_delete($conn)
{
  $stmt = "delete from mytable";
  $s = oci_parse($conn, $stmt);
  $r = oci_execute($s);
}

// Program starts here
$c = oci_connect("phphol", "welcome", "//localhost/orcl");

$starttime = microtime(TRUE);
for ($i = 0; $i < 10000; $i++) {
  do_insert($c);
}
$endtime = microtime(TRUE) - $starttime;
echo "Time was ".round($endtime,3)." seconds<br>";

do_row_check($c);  // Check insert done
do_delete($c);     // cleanup committed rows

?>
Load the URL http://localhost/~phphol/trans_time_autocommit.php several times and see how long it takes to insert the 10,000 rows.
Show Screenshot for Step
Show Screenshot for Step
The bigger row count shown in the first query is from the previous insertion in trans_autocommit.php.
Note: Your time values may differ depending on the hardware resources you are using.
9 .
Now review the trans_time_explicit.php script. The only difference in this script is that in the do_insert()function OCI_DEFAULT has been added so it doesn't automatically commit, and an explicit commit has been added after the insertion loop:
...

function do_insert($conn) {
  $stmt = "insert into mytable values (to_date('01-JAN-08 10:20:35', 
      'DD:MON:YY HH24:MI:SS'))";
  $s = oci_parse($conn, $stmt);
  $r = oci_execute($s, OCI_DEFAULT);  // Don't commit
}

...

$starttime = microtime(TRUE);
for ($i = 0; $i < 10000; $i++) {
  do_insert($c);
}
oci_commit($c);
$endtime = microtime(TRUE) - $starttime;

...
Load the URL http://localhost/~phphol/trans_time_explicit.php. The insertion time is less.
Show Screenshot for Step
In general you want all or none of your data committed. Doing your own transaction control has performance and data-integrity benefits.
Note: Your time values may differ depending on the hardware resources you are using.

Using Stored Procedures

PL/SQL is Oracle's procedural language extension to SQL. PL/SQL procedures and functions are stored in the database. Using PL/SQL lets all database applications reuse logic, no matter how the application accesses the database. Many data-related operations can be performed in PL/SQL faster than extracting the data into a program (for example, PHP) and then processing it. Oracle also supports Java stored procedures.
In this tutorial, you will create a PL/SQL stored procedure and call it in a PHP script. Perform the following steps:
1 .
Start SQL*Plus and create a new table, ptab with the following command:
sqlplus phphol/welcome
create table ptab (mydata varchar(20), myid number);
Show Screenshot for Step
2 .
In SQL*Plus, create a stored procedure, myproc, to insert data into the ptab table, with the following commands:
create or replace procedure
myproc(d_p in varchar2, i_p in number) as
begin
  insert into ptab (mydata, myid) values (d_p, i_p);
end;
/
Show Screenshot for Step
3 .
Review the code in $HOME/public_html/proc.php
<?php

$c = oci_connect('phphol', 'welcome', '//localhost/orcl');
$s = oci_parse($c, "call myproc('mydata', 123)");
oci_execute($s);
echo "Completed";

?>
4 .
From a Web browser, enter the following URL to display the output:
http://localhost/~phphol/proc.php
Show Screenshot for Step
The PHP script has created a new row in the ptab table by calling the stored procedure myproc. The table ptabhas a new row with the values "mydata" and 123.
Switch to your SQL*Plus session and query the table to show the new row:
select * from ptab;
Show Screenshot for Step
5 .Extend proc.php to use a bind variable. Change proc.php to the following (changes are in bold):
<?php

$c = oci_connect('phphol', 'welcome', '//localhost/orcl');
$s = oci_parse($c, "call myproc('mydata', :bv)");
$v = 456;
oci_bind_by_name($s, ":bv", $v);
oci_execute($s);
echo "Completed";

?>
The oci_bind_by_name() function binds the PHP variable $v to ":bv" and experiment changing the value inserted by changing the value in $v.
Rerun the following URL:
http://localhost/~phphol/proc.php
Show Screenshot for Step
Switch to your SQL*Plus session and query the table again to show the new row:
select * from ptab;
Show Screenshot for Step
6 .
PL/SQL stored functions are also commonly used in Oracle. In SQL*Plus, create a PL/SQL stored functionmyfunc() to insert a row into the ptab table, and return double the inserted value:
create or replace function
myfunc(d_p in varchar2, i_p in number) return number as
begin
  insert into ptab (mydata, myid) values (d_p, i_p);
  return (i_p * 2);
end;
/
Show Screenshot for Step
7 .
Review the code in $HOME/public_html/func.php
<?php

$c = oci_connect('phphol', 'welcome', '//localhost/orcl');
$s = oci_parse($c, "begin :bv := myfunc('mydata', 123); end;");
oci_bind_by_name($s, ":bv", $v, 10);
oci_execute($s);
echo $v, "<br>\n";
echo "Completed";

?>
Because a value is being returned, the optional length parameter to oci_bind_by_name() is set to 10 so PHP can allocate the correct amount of memory to hold up to 10 digits
Rerun the following URL:
http://localhost/~phphol/func.php
Show Screenshot for Step

Improve Query Performance

This section demonstrates some ways to improve query performance. Perform the following steps:
1 .
Review the SQL in $HOME/public_html/fetch_prefetch.sql
set echo on
drop table bigtab;
create table bigtab (mycol varchar2(20));
begin
  for i in 1..20000
  loop
   insert into bigtab (mycol) values (dbms_random.string('A',20));
  end loop;
end;
/
commit;
exit
This script creates a table with a large number of rows. From your sqlplus session, run the following:
connect phphol/welcome
@fetch_prefetch
Show Screenshot for Step
2 .
Review the code in $HOME/public_html/fetch_prefetch.php
<?php

require('helper.php');

function do_prefetch($c, $pf)
{
  $stid = oci_parse($c, "select mycol from bigtab");
  oci_execute($stid);
  oci_set_prefetch($stid, $pf);
  oci_fetch_all($stid, $res);
  return $res;
}

$c = oci_connect("phphol", "welcome", "//localhost/orcl");
$pf_a = array(1, 10, 500, 2000); // Prefetch values to test 
foreach ($pf_a as $pf_num)
{
  $start = currTime();
  $r = do_prefetch($c, $pf_num);
  $t = elapsedTime($start);
  print "Prefetch $pf_num - Elapsed time is: " . round($t, 3) .
        " seconds<br>\n";
}

?>
This performs the same query with different prefetch sizes. Prefetching is a form of internal row buffering. The number of rows in the buffer is the prefetch value. The larger the prefetch value, the fewer the number of physical database access are needed to return all data to PHP, because each underlying physical request to the database returns more than one row. This can help improve performance. PHP code does not need to change to handle different prefetch sizes. The buffering is handled by Oracle code.
The included script helper.php contains the simple currTime() and elapsedTime() timing functions, as well as some additional setup functions used later.
3 .
Load the following URL to display the output:
http://localhost/~phphol/fetch_prefetch.php
Show Screenshot for Step
Reload a few times to see the average times. Your time values may differ depending on your hardware resources, and so on.
The default prefetch size can be set in PHP's initialization file, php.ini. Prior to PHP 5.3, the default prefetch size was 10 rows. In 5.3, it is 100 rows. You should choose a suitable default value for your application, and useoci_set_prefetch() for specific queries that need a different value.
When using Oracle Database 11g Release 2 client libraries, row prefetching also benefits fetching from REF CURSORS.
4 .
This section shows the oci_bind_array_by_name() function that allows a PHP array to be retrieved from, or passed to, a PL/SQL procedure.
Review the SQL in $HOME/public_html/fetch_bulk.sql
set echo on
create or replace package fetchperfpkg as
  type arrtype is table of varchar2(20) index by pls_integer;
  procedure selbulk(p1 out arrtype);
end fetchperfpkg;
/
create or replace package body fetchperfpkg as
  procedure selbulk(p1 out arrtype) is
  begin
   select  mycol bulk collect
     into  p1
     from  bigtab;
  end selbulk;
end fetchperfpkg;
/
show errors
exit
This script creates a PL/SQL package that fetches from BIGTAB using a PL/SQL BULK COLLECT statement, and returns the results in a PL/SQL array. From your sqlplus session, run the following:
sqlplus phphol/welcome
@fetch_bulk
Show Screenshot for Step
5 .
Review the code in $HOME/public_html/fetch_bulk.php
<?php

require('helper.php');

function do_sel_bulk($c)
{
  $s = oci_parse($c, "begin fetchperfpkg.selbulk(:a1); end;");
  oci_bind_array_by_name($s, ":a1", $res, 20000, 20, SQLT_CHR);
  oci_execute($s);
  return($res);
}

$c = oci_connect("phphol", "welcome", "//localhost/orcl");

$start = currTime();
$r = do_sel_bulk($c);
$t = elapsedTime($start);
print "Bulk collect - Elapsed time is: " . round($t, 3) . " seconds\n<br>";

?>
This code calls the PL/SQL package and binds a PHP variable to hold the returned data array. No OCI8 fetch call is needed.

6 .
Load the following URL to display the output:
http://localhost/~phphol/fetch_bulk.php
Show Screenshot for Step
Reload a few times to see the average times.
Array binding is a useful technique to reduce database overhead when inserting or retrieving data.
This example doesn't print the returned results. If you want to see them, add "var_dump($res);" before the function return statement. The output shows the random 20-character data strings created byfetch_prefetch.sql, which you ran earlier.

Using LOBs: Uploading and Querying Images

Oracle Character Large Object (CLOB) and Binary Large Object (BLOB) columns (and PL/SQL variables) can contain very large amounts of data. There are various ways of creating them to optimize Oracle storage. There is also a pre-supplied package DBMS_LOB that makes manipulating them in PL/SQL easy.
To create a small application to load and display images to the database, perform the following steps.
1 .
Before doing this section create a table to store a BLOB. In SQL*Plus logged in as phphol, execute the following commands:
sqlplus phphol/welcome
create table btab (blobid number, blobdata blob);
Show Screenshot for Step
2 .
Review the code in $HOME/public_html/blobins.php
<?php
if (!isset($_FILES['lob_upload'])) {
// If nothing uploaded, display the upload form
?>

<form action="<?php echo $_SERVER['PHP_SELF']; ?>"
      method="POST" enctype="multipart/form-data">
Image filename: <input type="file" name="lob_upload">
<input type="submit" value="Upload">
</form>


<?php
} // closing brace from 'if' in earlier PHP code
else {
  // else script was called with data to upload


  $myblobid = 1; // should really be a unique id e.g. a sequence number


  $conn = oci_connect("phphol", "welcome", "//localhost/orcl");

  // Delete any existing BLOB
  $query = 'delete from btab where blobid = :myblobid';
  $stmt = oci_parse ($conn, $query);
  oci_bind_by_name($stmt, ':myblobid', $myblobid);
  $e = oci_execute($stmt);

  // Insert the BLOB from PHP's temporary upload area
  $lob = oci_new_descriptor($conn, OCI_D_LOB);
  $stmt = oci_parse($conn, 'insert into btab (blobid, blobdata) '
        .'values(:myblobid, empty_blob()) returning blobdata into :blobdata');
  oci_bind_by_name($stmt, ':myblobid', $myblobid);
  oci_bind_by_name($stmt, ':blobdata', $lob, -1, OCI_B_BLOB);
  oci_execute($stmt, OCI_DEFAULT);  // Note OCI_DEFAULT
  if ($lob->savefile($_FILES['lob_upload']['tmp_name'])) {
    oci_commit($conn);
    echo "BLOB uploaded";
  }
  else {
    echo "Couldn't upload BLOB\n";
  }
  $lob->free();
}

?>
This shows HTML code embedded in multiple PHP blocks. In particular, a PHP 'if' statement encloses the HTML code.The first time the script is loaded, the HTML upload form is shown. PHP has populated the form action name to call the same script again.

There is a direct relationship between the HTML form name name="lob_upload" and the special PHP variable$_FILES['lob_upload']. When the form is called with data, the script deletes any existing image from the table, and inserts the new picture.

The script shows the use of oci_new_descriptor() which is bound to the empty_blob() location. The LOB->savefile() method inserts the picture to the newly created row. Note the OCI_DEFAULT option tooci_execute() is necessary for the subsequent LOB method to work.
3 .
From your Web browser, enter the following URL to display the output:
http://localhost/~phphol/blobins.php
Show Screenshot for Step
It shows a Web form with Browse and Upload buttons. Click Browse.
4 .
Select oracle.jpg from the /home/phphol/public_html directory and click Open.
Show Screenshot for Step
5 .
Click Upload.
Show Screenshot for Step
The form action calls the script a second time, but now the special variable $_FILES['lob_upload'] is set and picture is uploaded. The successful echo message is displayed.
The image has been uploaded to the Web server.
Show Screenshot for Step
6 .
To show the image, review the code in $HOME/public_html/blobview.php
<?php

$conn = oci_connect("phphol", "welcome", "//localhost/orcl");

$query = 'SELECT BLOBDATA FROM BTAB WHERE BLOBID = :MYBLOBID';
$stmt = oci_parse ($conn, $query);
$myblobid = 1;
oci_bind_by_name($stmt, ':MYBLOBID', $myblobid);
oci_execute($stmt);
$arr = oci_fetch_array($stmt, OCI_ASSOC);
$result = $arr['BLOBDATA']->load();

header("Content-type: image/JPEG");
echo $result;

oci_close($conn);

?>
7 .
From your Web browser, enter the following URL to display the output:
http://localhost/~phphol/blobview.php
Show Screenshot for Step
Make sure there is no whitespace before <?php and no echo statements in the script, because otherwise the wrong HTTP header will be sent and the browser won't display the image properly. If you have problems, comment out the header() function call and see what is displayed.

Setting Trace Information

OCI8 has several functions that send meta data to the database when statements are executed. These are shown in many Oracle tools and are useful for application monitoring and tracing.
1 .To show two of the functions, review the code in $HOME/public_html/app_info.php
<?php

$c = oci_pconnect('phphol', 'welcome', 'localhost/orcl');
oci_set_module_name($c, 'Home Page');
oci_set_action($c, 'Friend Lookup');

$s = oci_parse($c, "select * from dual");
oci_execute($s);

$r = oci_fetch_array($s);
echo "Value returned is ", $r[0];

?>
2 .
From your Web browser, enter the following URL to display the basic output:
http://localhost/~phphol/app_info.php
Show Screenshot for Step

3 .
Review the SQL in $HOME/public_html/app_info.sql
col sql_text format a20
col module format a10
col action format a20

select sql_text, module, action
from v$sqlarea
where module = 'Home Page';

exit
This script shows SQL statements previously executed in the database by the Home Page module.

4 .
Open a terminal window and enter the following commands to run the SQL script.
sqlplus phphol/welcome
@app_info.sql
Show Screenshot for Step
The SQL*Plus script shows the meta data is saved with the statement. The meta data can be used for tracing or identifying the location in a PHP application of a misbehaving SQL statement. Note only the application information from the first execution of a statement is stored in V$SQLAREA.

Incorporating AJAX into Your Page

This section shows the basic technique of updating a section of a page without reloading the whole content. Perform the following tasks:
You can use a XmlHttpRequest to update a section of a page without reloading the whole page content. Perform the following steps:
1 .
Review the code in $HOME/public_html/ajax_id.php
This file simply echoes the parameter passed in.
<?php

if (!isset($_GET['id'])) {
  $id = 'No id passed';
} 
else {
  $id = $_GET['id']; 
}

echo "Id was: ", htmlentities($id); 

?>
2 .
From your browser, enter the following URL to display the output:
http://localhost/~phphol/ajax_id.php?id=185
Show Screenshot for Step
3 .
Review the code in $HOME/public_html/ajax_id.html
This file contains a JavaScript function, makeRequest().
<html>
<head>
  <script type="text/javascript">
  function makeRequest(id)
  {
     httpRequest = new XMLHttpRequest();
     httpRequest.open('GET', 'http://localhost/~phphol/ajax_id.php?id=' + id);
     httpRequest.onreadystatechange = function()
     {
        if (httpRequest.readyState == 4) {    // The request is complete 
          alert(httpRequest.responseText);    // Display the result
        }
     }
     httpRequest.send(null);
  }
  </script>
</head>

<body onload="makeRequest(185)">
<h1>Employee Lookup</h2>
<div id="descriptionNode">This page finds an employee</div>
</body>
</html>
4 .
From your browser, enter the following URL to display the output:
http://localhost/~phphol/ajax_id.html
Show Screenshot for Step
Click OK to dismiss the alert window.
Note: if you use Internet Explorer, you will need to edit ajax_id.html and change the XMLHttpRequest() call toActiveXObject("Msxml2.XMLHTTP") or ActiveXObject("Microsoft.XMLHTTP").
When the HTML page is loaded, the makeRequest() javascript function is called. It prepares an XMLHttpRequest request to call ajax_id.php. A callback function onreadystatechange is set. Finally the request is sent to the webserver asynchronously.
When the callback function is notified that the web server request has returned, the output from ajax_id.php is displayed by the alert() function. In web application, the Java script could be invoked by various
events and could be made to alter the content of the current page.
5 .Edit ajax_id.html and change 185 to 186.
Show Screenshot for Step
6 .Reload it in the browser. The new value is displayed. Click OK to dismiss the alert window.
Show Screenshot for Step
Note: You may also need to flush the browser cache to see the changed value.

Summary

In this tutorial, you have learned how to:
  • Create a connection
  • Use Database Resident Connection Pooling
  • Fetch data
  • Use bind variables
  • Use transactions
  • Call PL/SQL
  • Improve query performance
  • Use LOBs to upload and query images
  • Incorporate AJAX into your page

Appendix: PHP Primer

PHP is a dynamically typed scripting language. It is most often seen in Web applications but can be used to run command-line scripts. Basic PHP syntax is simple to learn. It has familiar loops, tests, and assignment constructs. Lines are terminated with a semi-colon.
Strings can be enclosed in single or double quotes:
'A string constant'
"another constant"
Variable names are prefixed with a dollar sign. Things that look like variables inside a double-quoted string will be expanded:
"A value appears here: $v1"
Strings and variables can also be concatenated using a period.
'Employee ' . $ename . ' is in department ' . $dept
Variables do not need types declared:
$count = 1;
$ename = 'Arnie';
Arrays can have numeric or associative indexes:
$a1[1] = 3.1415;
$a2['PI'] = 3.1415;
Strings and variables can be displayed with an echo or print statement. Formatted output with printf() is also possible.
echo 'Hello, World!';
echo $v, $x;
print 'Hello, World!';
printf("There is %d %s", $v1, $v2);
The var_dump() function is useful for debugging.
var_dump($a2);
Given the value of $a2 assigned above, this would output:
array(1) {
  ["PI"]=>
  float(3.1415)
}
Code flow can be controlled with tests and loops. PHP also has a switch statement. The if/elseif/else statements look like:
if ($sal > 900000) {
  echo 'Salary is way too big';
}
elseif ($sal > 500000) {
  echo 'Salary is huge';
}
  else {
  echo 'Salary might be OK';
}
This also shows how blocks of code are enclosed in braces.
A traditional loop is:
for ($i = 0; $i < 10; $i++) {
  echo $i;
}
This prints the numbers 0 to 9. The value of $i is incremented in each iteration. The loop stops when the test condition evaluates to false. You can also loop with while or do while constructs.
The foreach command is useful to iterate over arrays:
$a3 = array('Aa', 'Bb', 'Cc');
foreach ($a3 as $v) {
  echo $v;
}
This sets $v to each element of the array in turn.
A function may be defined:
function myfunc($p1, $p2) {
  echo $p1, $p2;
  return $p1 + $p2;
}
Functions may have variable numbers of arguments, and may or may not return values. This function could be called using:
$v3 = myfunc(1, 3);
Function calls may appear earlier than the function definition.
Sub-files can be included in PHP scripts with an include() or require() statement.
include("foo.php");
require("bar.php");
A require() will generate a fatal error if the script is not found.
Comments are either single line:
// a short comment
or multi-line:
/*
  A longer comment
*/
PHP scripts are enclosed in <?php and ?> tags.
<?php
  echo 'Hello, World!';
?>
When a Web server is configured to run PHP files through the PHP interpreter, loading the script in a browser will cause the PHP code to be executed and all output to be streamed to the browser.
Blocks of PHP code and HTML code may be interleaved. The PHP code can also explicitly print HTML tags.
<?php
  require('foo.php');
  echo '<h3>';
  echo 'Full Results';
  echo '</h3>';
  $output = bar(123);
?>
<table border="1">
  <tr>
    <td>
     <?php echo $output ?>
    </td>
  </tr>
</table>
Many aspects of PHP are controlled by settings in the php.ini configuration file. The location of the file is system specific. Its
location, the list of extensions loaded, and the value of all the initialization settings can be found using the phpinfo() function:
<?php
  phpinfo();
?>
Values can be changed by editing phpl.ini and restarting the Web server. Some values can also be changed within scripts by using the ini_set() function.
A list of the various oci functions include the following:
oci_bind_array_by_name
Binds PHP array to Oracle PL/SQL array by name
oci_bind_by_name
Binds the PHP variable to the Oracle placeholder
oci_cancel
Cancels reading from cursor
oci_close
Closes Oracle connection
oci_commit
Commits outstanding statements
oci_connect
Establishes a connection to the Oracle server
oci_define_by_name
Uses a PHP variable for the define-step during a SELECT
oci_error
Returns the last error found
oci_execute
Executes a statement
oci_fetch_all
Fetches all rows of result data into an array
oci_fetch_array
Returns the next row from the result data as an associative or numeric array, or both
oci_fetch_assoc
Returns the next row from the result data as an associative array
oci_fetch_object
Returns the next row from the result data as an object
oci_fetch_row
Returns the next row from the result data as a numeric array
oci_fetch
Fetches the next row into result-buffer
oci_field_is_null
Checks if the field is NULL
oci_field_name
Returns the name of a field from the statement
oci_field_precision
Tell the precision of a field
oci_field_scale
Tell the scale of the field
oci_field_size
Returns the size of the field
oci_field_type_raw
Tell the raw Oracle data type of the field
oci_field_type
Returns data type of the field
oci_free_statement
Frees all resources associated with statement or cursor
oci_internal_debug
Enables or disables internal debug output
oci_new_collection
Allocates new collection object
oci_new_connect
Establishes a new connection to the Oracle server
oci_new_cursor
Allocates and returns a new cursor (statement handle)
oci_new_descriptor
Initializes a new empty LOB or FILE descriptor
oci_num_fields
Returns the number of result columns in a statement
oci_num_rows
Returns number of rows affected during statement execution
oci_parse
Prepares Oracle statement for execution
oci_password_change
Changes password of Oracle's user
oci_pconnect
Connect to an Oracle database using a persistent connection
oci_result
Returns a field's value from a fetched row
oci_rollback
Rolls back outstanding transaction
oci_server_version
Returns server version
oci_set_prefetch
Sets number of rows to be prefetched
oci_statement_type
Returns the type of an OCI statement

Posted by at
Labels: , , ,

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)