$DSN = "oci8://user:passwd@host/sid?charset=ZHS16GBK";

if ($mode==1) {
$this->_connectionID = ($this->charSet) ?
OCIPLogon($argUsername,$argPassword, $argDatabasename, $this->charSet)
:
OCIPLogon($argUsername,$argPassword, $argDatabasename)
;
if ($this->_connectionID && $this->autoRollback) OCIrollback($this->_connectionID);
} else if ($mode==2) {
$this->_connectionID = ($this->charSet) ?
OCINLogon($argUsername,$argPassword, $argDatabasename, $this->charSet)
:
OCINLogon($argUsername,$argPassword, $argDatabasename);

} else {
$this->_connectionID = ($this->charSet) ?
OCILogon($argUsername,$argPassword, $argDatabasename,$this->charSet)
:
OCILogon($argUsername,$argPassword, $argDatabasename);
}