<?php 
$host="localhost:test"; 
$username="SYSDBA"; 
$password="masterkey"; 
$dbh = ibase_connect($host, $username, $password); 
$stmt = "SELECT id FROM users"; 
$result = ibase_query($dbh, $stmt); 
if ($result==0) 
   echo("<B>Ошибка!</B>"); 
?> 

<?php 
$host="localhost:test"; 
$username="SYSDBA"; 
$password="masterkey"; 
$dbh = ibase_connect($host, $username, $password); 
$stmt = "SELECT id FROM users"; 
$rs = ibase_query($dbh, $stmt); 
if ($rs) {
   while ($obj = ibase_fetch_object($this->rs, IBASE_TEXT) {
       // тут обрабатываем или складываем в массив
       var_dump($obj);
   }
}
else {
   $err_msg = ibase_errmsg();
   if ($err_msg)
      echo "<B>Ошибка:</B> $err_msg"; // я бы в этом месте Exception кинул
}
?> 

<?php
    $dbh = ibase_connect('localhost:mydb', 'sysdba', 'masterkey', 'UTF-8');
    $sth = null;
    $rc = null;
	
    try {
	  $sth = ibase_prepare($dbh, 'SELECT CODE_COLOR, NAME FROM COLOR WHERE CODE_COLOR = ?');
	  $code_color = null;
          $rs =  ibase_execute($sth, $code_color);  
  	  if (is_resource($rs)) {
              $object = ibase_fetch_object($rs, IBASE_TEXT);
              var_dump($object);
	  }
	  else 
	      echo 'It is not cursor';
    }
    finally {
      if (is_resource($rs))
        ibase_free_result($rs);
      if (is_resource($sth))
        ibase_free_query($sth);
      if (is_resource($dbh))
        ibase_close($dbh);	
    }
?>		

CREATE TABLE COLOR (
    CODE_COLOR    INTEGER NOT NULL,
    NAME          VARCHAR(30) NOT NULL,
    CONSTRAINT PK_COLOR PRIMARY KEY (CODE_COLOR)
);

INSERT INTO COLOR(CODE_COLOR, NAME) VALUES(1, 'красный');
INSERT INTO COLOR(CODE_COLOR, NAME) VALUES(2, 'синий');