ADOdb follows a similar pattern of DSN (Data Source Name) because it was modeled after the same original as PEAR. The original are, of course URL-like database names used by JDBC drivers.  The DSN syntax for Oracle is:

The “database” part in the expression above is the TNS descriptor of the database to which the connection is being established. The driver is “oci8”, same as in the case of PEAR DB.

When the DSN is defined, the new connection is established by the following sequence:

require_once('adodb/adodb.inc.php');
$DSN=”oci8://scott:tiger@local”;
$db=NewADOConnection($DSN);

The reader should notice the inclusion of the file, adodb.inc.php.  This file defines the basic ADOdb classes and must be included if ADOdb is to be used.

The code on the previous page creates a connection to the SCOTT schema on the database called “LOCAL”. As with PEAR DB, DSN can be split into separate fields for the database type, username, password and database descriptor. 

require_once('adodb/adodb.inc.php');
$db=NewADOConnection('oci8');
$db->Connect($database,”scott”,”tiger”);

The variable $database represents the TNS descriptor for the desired Oracle database.  For non-Oracle databases, the syntax is different and should be checked in the on-line manual.

In the PEAR DB section, connecting to an Oracle instance was explained in Example 20. The following example is Example 20 rewritten using ADOdb:

Example 25

#!/usr/local/bin/php
<?php
require_once('adodb/adodb.inc.php');
require_once('adodb/adodb-exceptions.inc.php');
 

try {
   $db=NewADOConnection("oci8");
   @$db->Connect("local","scott","lion");
   $sql="select * from emp";
   $sth=$db->Execute($sql);}

Notice the password for the user SCOTT was specified as “lion”, obviously incorrect.  When the example is executed, the following results:

ADOdb works with PHP5 and throws an exception when an error occurs. To initiate such behavior, the inclusion of the adodb-exceptions.inc.php file is needed, in addition to the adodb.inc.php file, as was done in the header. ADOdb also differs from PEAR DB philosophically, because ADOdb exceptions return the error code belonging to the underlying database, while PEAR DB returns its own error, portable across all supported databases.

Also notice the error was returned in the EXECUTE, not in the connect function. ADOdb was built for speed and attempts to pack as many operations together as possible. By actually trying to connect only before the execute, ADOdb can potentially save a trip across the network.  This can lead to errors being returned in unexpected places. That is exactly what makes exceptions such a good tool for exception handling.

The problematic password is replaced with the correct password and the following results:

The result is exactly the same as in Example 20.

Methods such as FieldCount()and FetchField() are explained in the next section. They do pretty much what they are expected to do. The only important function in Example 25 that was not explained before is the range function.  The range function is a very useful function that creates a range of numbers in a form of an array and is very useful in the foreach expressions. The following shows what the online manual says about the range function:

range

(PHP 3>= 3.0.8, PHP 4 , PHP 5)

range --  Create an array containing a range of elements

Description

array range ( number low, number high [, number step])

range() returns an array of elements from low to high, inclusive. If low > high, the sequence will be from high to low.

New Parameter

The optional step parameter was added in 5.0.0. If a step value is given, it will be used as the increment between elements in the sequence. step should be given as a positive number. If not specified, step will default to 1.

SEE CODE DEPOT FOR FULL SCRIPTS

http://www.rampant-books.com/book_2005_2_php_oracle.htm