(PHP 5)
ibase_connect — Open a connection to a database
$database
   [, string $username
   [, string $password
   [, string $charset
   [, int $buffers
   [, int $dialect
   [, string $role
   [, int $sync
  ]]]]]]]] )Establishes a connection to an Firebird/InterBase server.
In case a second call is made to ibase_connect() with the same arguments, no new link will be established, but instead, the link identifier of the already opened link will be returned. The link to the server will be closed as soon as the execution of the script ends, unless it's closed earlier by explicitly calling ibase_close().
database
       The database argument has to be a valid path to
       database file on the server it resides on. If the server is not local,
       it must be prefixed with either 'hostname:' (TCP/IP), 'hostname/port:'
       (TCP/IP with interbase server on custom TCP port), '//hostname/'
       (NetBEUI), depending on the connection
       protocol used.   
      
usernameThe user name. Can be set with the ibase.default_user php.ini directive.
password
       The password for username. Can be set with the
       ibase.default_password php.ini directive.
      
charset
       charset is the default character set for a
       database.
      
buffers
       buffers is the number of database buffers to
       allocate for the server-side cache. If 0 or omitted, server chooses
       its own default.
      
dialect
       dialect selects the default SQL dialect for any
       statement executed within a connection, and it defaults to the highest
       one supported by client libraries.
      
roleFunctional only with InterBase 5 and up.
sync
   Returns an Firebird/InterBase link identifier on success, or FALSE on error.
  
If you get some error like "arithmetic exception, numeric overflow, or string truncation. Cannot transliterate character between character sets" (this occurs when you try use some character with accents) when using this and after ibase_query() you must set the character set (i.e. ISO8859_1 or your current character set).
Example #1 ibase_connect() example
<?php
$host = 'localhost:/path/to/your.gdb';
$dbh = ibase_connect($host, $username, $password);
$stmt = 'SELECT * FROM tblname';
$sth = ibase_query($dbh, $stmt);
while ($row = ibase_fetch_object($sth)) {
    echo $row->email, "\n";
}
ibase_free_result($sth);
ibase_close($dbh);
?>