PHP 连接 Oracle 出现中文乱码问题

$conn = oci_pconnect('scott','tiger',
"(DEscriptION=(ADDRESS=(PROTOCOL =TCP)(HOST=192.168.0.1)(PORT = 1521))(CONNECT_DATA =(SERVER = DEDICATED)(SERVICE_NAME=jocsbk)))",
'AL32UTF8');

while ($dat = oci_fetch_row($cur)) {   
  print_r(iconv('gb2312', 'utf-8', $dat[0]));   
}  
//或者
while ($dat = oci_fetch_row($cur)) {   
  print_r(mb_convert_encoding($dat[0], 'utf-8', 'gbk'));   
}

$c1 = oci_connect("scott", "tiger", $db, 'UTF8');